last night I installed new version of Debian - 6.0. I like it in general, but my only problem was my graphic card. My laptop - Thinkpad T43p - has dedicated card from ATI - FireGL V3200. In "Lenny" I used non-free driver from ATI - so-called "fglrx" kernel module and "Catalyst" software. So, my xorg.conf file had "fglrx" in the "Driver" property. After update X-server failed to start. I searched a bit, found out, that I had to recompile "Catalyst" for version 6.0 again. I did it, and then tried to start "aticonfig --initial" to create new xorg.conf file. "aticonfig" ended with "no supported adapters" error. After another 30 minutes of searching I discovered, that the latest version of "Catalyst" (the one, which is shipped with Debian 6.0 "Squeeze", version 10.9) DOES NOT support my card anymore. The last version of "Catalyst" with FireGL-support was version 8.12.
So, to make the story short: some cards are not supported by ATI/AMD in their Linux driver anymore. It means, that we (the owners of those cards) MUST use free driver "radeon", if we want to keep our computers.
So, I plan to post further impressions from "Squeeze" later.