This is the best I managed for Jupiter using the EOS 1000D with the video hack. Took a lot of post-processing to bring out any detail. I never thought of trying the n900 - as I attach the camera direct to the telescope and just use the sensor (avoiding the camera lenses). You can use anything with a sensor - I rigged up a CCTV camera to take these images of Mars & Saturn.

There might be another way of approaching this - with the CCTV camera, I hooked that up to a HDD recorder, then processed the video. You might find taking video with the n900 produces better results - you take the frames recorded and put them into something like Registax to stack them and average them to produce a better image. You'd still need to track the object quite accurately though.