I downloaded this awesome application called PhoneStream, created by tetris11_. It allows one to stream either the front/back camera or microphone to a Desktop PC either through VLC media player (windows/linux), Xout (linux), or one can use your N900 as a primary webcam (linux). It can also record a file locally to the phone, or record onto ones desktop (VLC or linux).
Above I am streaming video from my Nokia N900 (192.168.0.9 on port 4788) and receiving it via VLC Network Media Stream on my desktop PC (192.168.0.5 on port 4788). All done via WIFI.
It is really easy to configure PhoneStream. In the MainWindow type in the address of the PC you want to stream too, a port (anything). Select the type (video or audio). Great news, both cameras on the N900 are supported, although the camera on the back has better quality. I tried out the front camera and it worked but requires good light.
PhoneStream supports both Windows and Linux and depending what system you have will greatly decide what option one chooses from the To pulldown:
Hit the stream button and a message pops up telling one what to do on the desktop side.
I used VLC for Windows and followed the above instructions.
After entering the address all there is to do is hit play and the stream can be viewed on the screen.
One can find a full set of instructions on the [Announce] PhoneStreamer – Nifty little app for streaming to your PC page over talk.maemo.org.