Beta 2 was released this morning as the open-source developers aim for "a rock-stable, fast and beautiful release" to happen in January.
Among the changes to look forward to with KDE 4.10 is the expanded use of Qt Quick within KDE Plasma Workspaces, a new KDE screen locker, animated wallpapers support, faster indexing with Nepomuk, color correction support, improved Plasma notifications, multiple enhancements to the Kate text editor, and much more. The first beta was released a couple weeks back
while this second beta provides more bug-fixes and translation updates.
More details on the second beta of KDE 4.10 can be found from today's press release