http://www.frogatto.com/
guys are developing new platformer for Win32, Mac, Linux, later for iPhone.

Has very nice graphics (8bit pixelart), just like in old days.

Code is open, graphics is not

2010-05-13 20:36:34
Post about very nice 8bit platformer backgrounds. Inspiring

http://www.frogatto.com/devforum/index.php/topic,75.0.html

2010-05-15 23:40:14
Post about tiles used in the game:

http://www.frogatto.com/devforum/index.php/topic,28.0.html

Published older art:

http://www.opengameart.org/content/old-frogatto-tile-art