Update: There is now a patch to activate DisplayPort on Lion for 5870 and some 5770 cards. See this post.
As expected, the video drivers in the release version of OS X Lion (10.7) are extremely similar to those found in 10.6.8. That means that the same issues experienced with 10.6.8 apply to the release version of Lion.
Specifically, all unofficial 5770 and 5870 cards will have DisplayPort deactivated, and some 5770s will render the system unbootable.
There is now a (partial) solution to the DisplayPort issue!
Unfortunately, for many double-slot 5770s there is no solution to the no-boot issue.
Because of this, I would recommend NOT installing Lion if:
- you are running a 5770 double-slot version with (DisplayPort and HDMI) or
- you run a 5870 or 5770 and use the DisplayPort/MiniDisplayPort for your only display, and this is your only graphics card
Backup first: It’s always a good idea to make a backup of your boot volume (i.e. main drive, usually called “Macintosh HD”) before upgrading to a new OS. Super Duper is an excellent software package for doing this, or you can use Disk Utility to clone a non-booted volume to another disk or partition.