I was wondering if there is any way to trick Skype to use the back camera. There was an older thread on this issue, but I think people were a bit on the wrong track, so here is my idea:
First, we find out how exactly is skype reading the video info. There is a file called videohost in /usr/lib/skyhost
Looking at the strings, I found: /tmp/videoplayback.%s and /tmp/videorecord.%s
.%s means a runtime set variable. There is no file with that name in /tmp/ while skype is not active. I don't have anyone on my list now with video chat capabilities, but I would assume this file will be created when engaged in a video chat.
I am not sure who creates that file though, if it is skype itself or some other script or binary. I looked through a lot of files for that name, but couldn't find it in any other file.
If the file is created by some other program, what we can do is to try and trick skype to use another file altogether (our file). This can be done by editing the binary with a hex editor. Then we could make a symlink or something to the front camera.

If someone is technically inclined and can test if/how the file "/tmp/videorecord.%s" is created, please post here. If not, I will try my luck tomorrow when hopefully someone with a video camera on my list can log in. Oh, and if you are going to try, log in by ssh so you won;t have to use the small keyboard/screen while talking on skype.

After further research, the skype libs are referenced by /usr/lib/telepathy/telepathy-spirit (which I guess is the module responsible for skype).
There is also a file there called telepathy-stream-engine that MIGHT be the mother of the streaming engine for all the telepathy plugins (gtalk, skype, etc.). That thing is open source, so maybe someone more familiar with Linux can download it and see how it works?
This binary is probably modified by Nokia, but maybe we can see where it gets the video source from..