As per title, does Spotify Linux preview work for 12.10? If so, are there any ad-blocking software that will work for it?
I was originally going to post something along the lines of "well, not that much has changed internally between 12.04 and 12.10, so it should work", but that's not a very good answer. :) So I went ahead and installed Spotify in a 64-bit 12.10 VM. I can confirm that the program works and I was able to log in and such. I don't anticipate that you will run into many problems, assuming that things worked fine for you on 12.04.
As for ads, well, I'd say the easiest way around that is to shell out 5$ and go for the unlimited membership, but I understand that this isn't always an option for people. I don't have any experience with ad blocking in Spotify, but I can at least say that blocking the audio ads is much harder than the client popups, and the audio ads are quite a bit more annoying than the banner ads (and ultimately what convinced me to go premium).