URGENT: Due to a lack of Mac OS X testers, Pinta 1.1 is not yet available as a stable release. Pinta is a simple drawing utility and image editor with a clean interface and an interesting set of tools.
In any case, Pinta does look promising, so we'll keep an eye on this handy little editor as it grows. According to Pinta's developer, the program is still at an early stage of development – which may be the reason why some of its tools are not available yet.