Following up on Canonical's announcement, what is Ubuntu for phones, where can I download a copy of the OS to run on my phone? And how do I know if it's compatible with my phone?
Ubuntu Touch / Ubuntu for Phones as the name implies, is the Ubuntu version for Mobiles (Smartphones & Tablets). This is still in DEVELOPMENT and any mobile phone right now would be a DEVELOPMENT PREVIEW, which means an unfinished, for test only product.
(Check at the bottom of this answer for updates)
Right now is too early to tell how Ubuntu Touch will work, will be sold, how the software will be integrated, how to get the software and work on it/with it or even be compatible with an Ubuntu Desktop.
The link you provided about Ubuntu for Phone is just a presentation of a new product, same as Ubuntu for Android and Ubuntu TV, they are being worked on for a future version but at least they have being announced so end users and developers know where Ubuntu is going.
We can see right now for example:
Looks, Design, Features and Requirements
Information for Developers
Email Contact for Developers: email@example.com
News About Ubuntu for Phones
Video in Phoronix about Mark Shuttleworth talking about Ubuntu on Smartphones
"Prediction" by CNN that Ubuntu will "Fail" - I added this part to make a personal statement about it, first as one of the comments found there shows:
Funny thing that there are several windows 8 phone videos on YouTube with 50k - 500k views and they are some 2 - 11 months old. Ubuntu-phone video has almost 1M views after two (2) days...
If you look at most Windows 8 videos and then look at that one (1) video of the Ubuntu for Phone ad you will see that it is true. It is important to know that Ubuntu for Phone is not just a normal smartphone and there is no 10 users that will end up buying one. It will have several smart ways of connecting it to a PC or TV. It can actually be used as a PC and it will have many features that will work out of the box with any Ubuntu computer (And also with Windows) integrating itself with Unity, the HUD and other Ubuntu features. This are just to name a few since there are many surprises to be seen from here until we see 13.04, 13.10 and 14.04.
The planned design style, I for one finding it awesome, it is very well made taking ideas from Unity itself while thinking on how to be more friendly to the user on phones. The hardware that is optimized is very good and I know that I will not be the only one saving up for one of this when it comes out. All of this is just my personal thoughts about it but wanted to leave some information noted from day one. If you have seen the video, you will have noticed all the information Mark Shuttleworth mentions and how well thought out the Ubuntu idea for phone is.
In WebUpd8 we can see a quoted message about Ubuntu phones not ready for purchase but they are starting to work with partners to start selling them before the end of 2013. So at least until the end of 2013 when Ubuntu Smartphones start to sell, there will be little information about this.
Also remember that Ubuntu for Phones, TVs and Tablets is a milestone set between 13.10 and 14.10 when Unity's integration on all types of hardware will be complete or near completion (Less bugs, better hardware support, better ARM support, etc..).
Will my Android Phone work with Ubuntu for Phone? Will it be an alternative?
Ubuntu for Phone will be another OS alternative to Phones, specially Smart Phones, that works with any phones that carry Android and have the minimum hardware requirements posted above. Phones like Samsung, HTC, Sony, LG and others that offer Android will be able to install Ubuntu for Phone on them. Of course, this will not be an App for Android, instead it will replace Android on that phone. So not only will new phones come with Ubuntu pre-installed, but it will also work on already existing Android phones
UPDATE 6 Feb 2013 - In Slashdot we can see an article about Ubuntu Smartphones shipping in October which points to a wsj article about Ubuntu Smartphones, including a link to Ubuntu Smartphone Designs. Pretty neat and open way of providing users with the ideas behind the design. This will truly turn into something big once users know they can be part of it's design. Another link is the OMGUbuntu post about Ubuntu Phones
UPDATE 18 Feb 2013 - In The H, we can see an article about Developer Preview for Ubuntu Phones which mentions an article in the Canonical Website that mentions the releases of the Developer Preview for Ubuntu Phones on the 21 Feb 2013.
UPDATE 19 Feb 2013 - Ubuntu has released the first Ubuntu Tour for Tablets. You can see the website at http://www.ubuntu.com/devices/tablet
You can also see the video here: http://www.youtube.com/watch?v=h384z7Ph0gU
UPDATE 21 Feb 2013 - The Ubuntu Phone, Tablet Developer Preview has been released
UPDATE 22 Feb 2013 - The Ubuntu Phone Porting Guide was unveiled
You can also visit the official Touch site
There is already a 'working' build for the Samsung Galaxy Nexus (? i9250) smartphone.
The code will initially be released as a file which can be installed on Samsung's Galaxy Nexus phone, replacing Android.
There was a recent media presentation in London, and engadget.com got to play with one ..
This is no ordinary Galaxy Nexus. Instead of Android, it's running a very different Linux-based OS -- the long-awaited mobile version of Ubuntu -- which comes with a new UI adapted for smaller screens. We've played with the phone briefly and we'll have a proper hands-on video for you shortly, but in the meantime there are a few salient features to report. ..
Canonical's preview of a smartphone- and tablet-friendly flavor of Ubuntu has finally arrived for folks willing to flash a Galaxy Nexus, Nexus 4 or a Nexus tablet. Shuttleworth and friends stress that the release is intended for developers and enthusiasts ..
And, along come the nay-sayers ..
Despite all of the giddiness though, I have not seen any phone makers step up and say they will produce and sell an Ubuntu phone. I think other than one or two strictly for the curiosity factor, we probably won't see a headlong rush to manufacture Ubuntu phones either. We might see a CyanogenMod type of group develop an Ubuntu that can be installed on rooted versions of Android phones or maybe WebOS/Palm phones, heck maybe even a Windows phone. But, by and large, Ubuntu is not going to challenge Microsoft or even BlackBerry for smartphone market share, let alone Apple or Android.
Ubuntu for Phones is a mobile version of the Ubuntu operating system.
The OS is not publicly available, nor is there an available device running it. All that has happened is that the product has been announced and the SDK released.
Late february 2013: