Today I've read an article that every position of Rubik's Cube can be solved in twenty moves or less. See : http://www.cube20.org/

On youtube there is a video of an andriod phone controlling a Lego Mindstorm creature which can solve a Rubik cobe in a few seconds.

http://www.youtube.com/watch?v=ylFb4pqAUd8

This would be a killer-app for the N900

EDIT:
Just found that a N95 can also do the trick :

http://www.youtube.com/watch?v=Q7P7GfKFw90