Pinta is a simplified image editor based on Paint.NET (and thus it uses Mono), designed to serve as an alternative to GIMP for casual users. Pinta 0.5 has been released yesterday with new features, such as multiple image support, procedural brushes (painting effects with new procedural paint brushes, such as splatter, squares, circles, and grid) and a clone stamp tool which you can use to easily remove unwanted objects from photos:
Other smaller enhancements have been added to Pinta 0.5, like save/load color palettes, TGA file support or support for choosing the JPEG compression level.
To install Pinta 0.5 in Ubuntu 10.04 Lucid Lynx or 10.10 Maverick Meerkat, use the following commands:
sudo add-apt-repository ppa:moonlight-team/pinta
sudo apt-get update
sudo aptitude install pinta