I'd suggest also emailing your file (or providing a link at Dropbox). Call it Plan B, in case the connection is slow or whatnot. (I've seen it happen.)
Yes, I was actually expecting them to ask for this, and am a little surprised that they haven't yet (interview is Tues. morning). I didn't even know that this Skype screen sharing existed until I started looking into it when the weekend arrived and they hadn't requested my Powerpoint. Of course, I tend to adjust talks right up to the last minute (sometimes literally), so not having to provide things in advance is very nice.