You could just open up your skin's _main.php file, and then stick the html code that is the 'Skype Me' button into the skin...

But if you want it so a 'Skype Me' button apears for each author of a blog, then that get's a bit trickier, atm, it would be 'hard' to do with the 1.8 release, as a user's fields are not dynamic. - If that makes any sense.

So in a short answer. Not yet.