I'm going to add SSD disk to my Ubuntu computer. Is there any known problems with PCI-E based SSD disks in Ubuntu (this, for instance)? Or should I prefer SSD disk with SATA interface to achieve maximum compatibility with Ubuntu OS? I use Ubuntu Server 8.04 now, but I'm ready to upgrade to 10.10 if necessary.
There are indeed some PCI Express SSDs that don't work well, but most of them do. They are basically a RAID controller with discs on one card you see, so same as with raid controllers: The more expensive ones generally work, the cheaper one's may not work perfectly.
You should therefore make sure you can give it back should it not work.
The one you linked, the OCZ RevoDrive, is known to work.
I would strongly recommend you upgrade to 10.10.
I don't own an SSD myself, but I have heard much talk about the 'TRIM' function, support for which was only relatively recently added to the Linux kernel in version 2.6.33.
Ubuntu 10.10 contains version 2.6.35 of the kernel (10.04 contains 2.6.32 & 8.04 contains only 2.6.24).