I am looking to learn about mobile operating systems and will be taking a look at how Android works. Can anyone here please direct me to some reading material and tutorials that will be of use. I intend to get involved with development of mobile OS. In particular I am interested to find out which languages actually are used as at the moment I only know this might be used or that might be used.

I am a computer science student and have some time on my hands to look at things that interest me in more detail, so I thought I would visit a few forums, and see what advice is given. I am aware I will need to spend a lot of time reading and practicing new concepts, but I am willing to do this.

Thanks in advance.