No idea of a release date, but most likely it's a couple of weeks ahead. I have a Radeon 9700 Pro myself, so I'm eager to get fresh drivers as well.
About the FX5800...well, when it came, people were disappointed with the performance - a Radeon 9700 killer was expected, not something that performed worse and cost more. What turned most people off about the FX5800, however, was the noise level (more like a vacuum cleaner than like a computer). Nvidia made a cooling "solution" that makes the card occupy two (2!) PCI slots. There were some versions of the FX5800 retailing with water cooling (!!). Now that tells me something about what people are willing to do to get rid of the boeing 747 in their box.
Read more reviews of the FX5800, and then read reviews of the FX5900. The FX5900 is a lot quiter, plus it's faster. There is no reason whatsoever to get the FX5800...well, unless you're a collector or something.
