AMD wants to turn that around. Today they issued a press release announcing the launch of an overhauled Radeon driver for Linux. According to them, performance gains as high as 90% are seen in OpenGL titles. They are so pleased with their new driver, in fact, they have linked to a third party review of it.
The driver adds a host of other long-awaited features, such as AIGLX support. This gives me a good boost of hope for AMD's success in moving video cards, and anyone who is using a Radeon in Linux should give the new driver a try.