The easiest answer is this:

If you don't know any programming languages, learn something high-level (e.g., Python). If you want your apps to have a GUI, learn GTK+.

If you use these two technologies, you won't even (mostly) need to setup the Maemo SDK, although many people will suggest that you take the time to do so (well, except for khertan, who will tell you to develop your apps on your tablet with his own PyGTKEditor app).

I'd also suggest learning Qt so that you'll have an easier time of porting to Maemo 5+.

If you already know a programming language (C, Ruby, even PHP), there are several methods of creating apps for Maemo 4.

But, alongside all of this advice, you really need to read (and memorize) this:

http://maemo.org/maemo_release_docum...on/maemo4.1.x/

Almost everything you need to know is available by clicking on the big DEVELOPMENT button on the top of this page.

Tim