Maemo uses a standard Linux OS with GTK/X11 for user interface and ESound for audio. The display is 16bpp, the audio appears to be fixed at 44.1kHz, but you can change the other parameters.

As far as development tools go, your best bet will be to install Ubuntu7 ("Gutsy Gibbon") and Maemo SDK+ (based on ScratchBox2 that will be installed automatically). After that, you should be able to use Maemo GCC and packaging tools by prepending their names with "sb2":

gcc hello.c - your local Ubuntu gcc
sb2 gcc hello.c - Maemo gcc

To transfer your application to the tablet, install SSH server on the tablet and use standard scp/ssh tools from Ubuntu7 to copy files to the tablet and run them there.

Links:

Writing a new application:
http://maemo.org/development/documen...maemo_4-0.html

Porting existing application:
http://maemo.org/development/documen...ing_guide.html

Installing Maemo SDK+:
http://maemo-sdk.garage.maemo.org/install.html