The best place to start is the Sugar on Ubuntu page on the Sugar Labs wiki.
The Ubuntu Sugar Team, which I (cheer)lead, has finally synced Sugar 0.82 from Debian into Intrepid. There are probably a whole bunch of bugs to be discovered in the packaging and setup, so if you’re interested in Sugar, and running Intrepid, please install, test, file bugs, and we’ll get them sorted out ASAP before Intrepid releases. The Sugar Team’s TODO list is on our Packages page. If you want to get involved, contact me or show up in #ubuntu-sugarteam on freenode.
Launchpad now has a Sucrose project, representing the Sugar components as well as some of the packaged activities, which gives a nice overview of what makes up Sugar.
I’ve updated Sugar and some of the packaged activities to the latest stable 0.82.x releases in the Sugar Team PPA. If you’re running Hardy this is the repository to use for the freshest Sugar experience this side of building from source!
I should have the rest of the activities updated in the next few days.