From the Apple product preview page:

Panther will include a final X11 window server for Unix-based apps, improved NFS/UFS, FreeBSD 5 innovations as well as support for popular Linux APIs, IPv6 and other important acronyms.

I hope I’ll be able to launch X apps from the Dock, that would be really useful…like I used to be able to do with OroborOSX ;). “Other acronyms”…that’s intriguing.