| At the same time, it also includes a number of features not seen in any of these languages.

I tried looking around for the new features and motivation for this language. The intro page (http://tart.googlecode.com/svn/site/intro/overview.html) opens as source for some reason (on FF6 and safari).

EDIT: Okay, intro page does have some features, although not exactly new (gc) ... hard to read due to rendering as source.