Hi,
currently skype does not support the '--display' command line switch. The actual code to process --display should be a standard function of the qt library. This way of specifying on what screen skype is supposed to start up on is needed for restoring the skype window on the correct x screen after logging in again.
Additionally the this information needs to be include in the clone and restart command in the session manager's data.

I just implemented this for pidgin, and it ended up being around 7-8 lines of code... now since I can't do that for skype, I hope some developer is reading this :-) . It'd be really nice to have this feature for people with two screens!

If any more details are needed, just ask me or post here.

Thanks,
~David