Not to disrespect Ubuntu, but Jaunty must be the worse release they have made in a long time. Whether it be an unusable desktop because of a poor kernel – upgrading to 2.6.30 is a good idea – or just poor packaging – md overwriting the mdadm.conf file? WTF? See here and here for the workaround lists, and here to fix the md issue.
Karmic is getting good reviews. Lets hope its an easy upgrade and sets the scene for an amazing 10.4 release.