A few months ego I purchased Nokia N800 device and since then I'm itching to write some code for it. I know that some of the application I'm running are written in Python and that there is a Mono port for the Maemo platform as well.
Basically what I'm asking is:
The Hildon framework is made up of GTK+ extensions, so the language is C. You can use C++ wrappers (maemomm) too. Or you can go with pymaemo for building apps with Python, which to me is much easier than C or C++. I've also seen an attempt at a ruby port, but have not followed up with that project recently.
For the development environment, there is "scratchbox", which gives you a sandbox for compiling and running your app. Here's a link on how to set up a scratchbox development environment. (It sure took me a long time to get everything setup.)
You'll have to use Linux as your development machine because your Nokia N800 is really a mini Linux computer.
If you want to have an IDE experience, try the ESbox plugin for Eclipse.
Have fun hacking!!!