first of all, i am really happy with the arduino, nice little thing... ;D
but it gave me a hard time when i wanted to integrate some c-code - so for your reference or (even better) so that you can change this behaviour, i'll give you more details.
i used the test.zip i found on the website to get started. i was sure the code runs (tested it outside the arduino environment), but i kept receiving linker errors in arduino. the problem was the following: since i wrote c code, the filename suffix was ".c". but the arduino toolchain doesn't seem to retain the #include-directive when c files are given in the library, so my pde was translated to an unusable cpp file. when i changed my filenames to ".cpp" suffixes, everything went fine.
so, is there an explanation for this behaviour (i'm new to arduino, so maybe i don't see the point) or is this a not-intended behaviour?