Rotatedaemon is a project mainly written in C++ and C, it's free.
A daemon for Maemo to rotate applications all four directions.
rotatedaemon is a C++ conversion (and enhancement) of a script called 'rotate.py' for Maemo (original author unknown).
Basically, it rotates applications - and not just landscape or portrait, reverse landscape/portrait are supported too.
It also supports a granular blacklist feature (to avoid rotating unstable applications), unlike rotate.py.
I was going to do a fair bit more with this, but really, there aren't many applications that work well in portrait mode.
All contact to do with this code should go to: [email protected]
Patches welcome.