I did the update this morning and we’ve got a very stable, very nice 4.0 release of Typo. Scott has also mentioned that there is support for migrating from other blogs such as wordpress and moveable type as well as alot of other new features and fixes.
svn update if you’re using the trunk version and then
rake migrate. If you get an error that the folder tmp/cache is not locked then use
rm -rf tmp/cache will take care of that issue.