Reports indicate that Apple has seeded an updated version of Panther.
The original Panther that was distributed at WWDC carried a build number of 7A179. A subsequent 'Test' Software Update brought Panther up to build 7A202, with improvements in Expos, Mail and iChat.
Friday, Apple seeded developers with Panther 7B21, but with few details on the changes are provided. This build is said to incorporate extensive bug fixes, however.