Check your software update panel -- 10.1.1 is now available (along with the new Airport software). According to Apple, the update includes improved support for USB and FireWire devices, improvements to CD and DVD burning, enhanced AFP, SMB and WebDav networking (maybe the iDisk will be usable on WebDAV now!), and improved printing support. Mail and the Finder have also been updated.
UPDATE: Apple has posted a very thorough what's new in 10.1.1 article on their site.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20011113173420525