I'm programming lazarus with n900.

That's freepascal together with a Visual development GUI.

http://wiki.freepascal.org/Setup_Cross_Compile_For_ARM

That works perfectly.
You can compile for gtk, command line or even for QT.

Here are the qt-bindings:
http://wiki.freepascal.org/Qt4_Maemo_Binding

I think that the same instructions will work also for N9.

It's very a big pleasure to program pascal on n900.

You can run the program on a PC with Windows or Linux.
Then you crosscompile it to arm and everything works even with the graphical elements of QT.
You can even compile for Hildon-Design.

I can even compile on device big projects. The fpc compiler is very fast on the n900.
But the IDE of Lazarus I didn't compile on the n900.
So, if you really want to program on the device, you have to do it by hand with an editor. But that works quite good.