A new beta set of Catalyst drivers was spotted at one of the vendors. This is revision 9.10 beta (build 8.660 RC7) and come with full Cypress (Radeon 5800 series) support.
We have a discussion thread open on these drivers right here.
ATI Catalyst 9.10 Beta Windows 7 | Vista (32|64)
ATI Catalyst 9.10 Beta Windows XP (32|64)
