AMD will once again be months late in supporting the newest X.Org / Linux kernel releases. With X.Org Server 1.10 there was an ABI break, and then a last-minute video ABI break when RandR 1.4 was removed, which renders this binary driver inoperable atop Ubuntu Natty.
If you're running a Linux desktop with updated X stack, there's prompt support in NVIDIA's binary driver and the open-source AMD / Nouveau / Intel drivers will work fine, but the Catalyst support is not to be found. Don't expect to see it in Catalyst 11.4 either, but Catalyst 11.5 in May is where AMD should finally have the final xorg-server 1.10 ABI supported, due to the last minute ABI break before the 1.10 release in late February.
We had been wondering for months whether AMD would have on-time X Server support this time around, but they missed the train. AMD had an internal Catalyst build working on the earlier X.Org Server 1.10 ABI back in January, but due to their development cycle and then the last minute video ABI break by the X.Org developers, the situation is again not ideal.
This has been a problem for years now with an Ubuntu Linux release approaching and AMD still not having out a supported driver, so they end up providing Canonical with an early driver copy that's not yet publicly released via AMD.com or in other repositories. It's been a tradition that's been going on since at least Ubuntu 8.10 (after that my memory gets a bit fuzzy and quickly searching through my old articles).
Right now in the Natty repository for Ubuntu 11.04 is a broken fglrx 8.80 package (Catalyst 11.3 is in the fglrx 8.83 series). The first Ubuntu Beta is due out on Thursday following by the second beta on the 14th of April when the beta freeze occurs. This means AMD will likely provide Canonical with a Catalyst 11.5 pre-release sometime in the next two weeks while the official release of that will be out in May. The Ubuntu 11.04 final release is scheduled for the 28th of April.
At least AMD continues to make progress on their open-source strategy for which they can be applauded by Linux desktop users.