Dragon Player has been made default in Kubuntu 10.10 instead of Kaffeine (I'm not really up to date with what's happening in Kubuntu, but it seems Kaffeine was default in Kubuntu 10.10 until now - at least according to the changelog of the kubuntu-meta package). A while back, the Kubuntu developers said they were considering VLC to be the default media player but unfortunately this didn't work out as expected. I'm not sure what are the reasons for this (since the news came from the kubuntu-meta changelog), but most probably there were some license/legal issues so they had to go with Dragonplayer.
Chromium was made default until UNE 10.10 alpha 3 at which point a decision had to be made rather or not to stick with Chromium or go back to Firefox - since Ubuntu 10.10 alpha 3 is about to be released (in 2 days), the decision came: Firefox will stay as the default browser in Ubuntu Netbook Edition 10.10, but Chromium has been moved into the main repository. The reasons include:
* We don't have a plugin installer, ie. if you go to a Flash site it sends you to Adobe's webpage instead of just installing the plugin.
* No langpacks or translations support in lp so we can't translate Chromium, we have to depend on upstream to do it in one huge thing. :(
* Doing all the xulrunner packaging changes in order to get the CD size down AND switching to chromium in one cycle is currently not feasible with the people we currently have.
You can read the whole motivation behind this @ Ubuntu Desktop mailing list.
And finally: An email on the Ubuntu MOTU mailing list points out that Ubuntu Tweak is in the "new queue" for Ubuntu 10.10 Maverick Meerkat which means Ubuntu Tweak might finally be added to the official Ubuntu repositories. Until now, you had to add a PPA or manually download a .deb to be able to install Ubuntu Tweak.