However, we found an iPhone app called "iVoice", and gave it a try for the Canada Rocks show last week with Orchestra London (all Canadian songs — fantastic show!). Katalin and Kathryn and I were rehearsing in the hotel on Thursday night and realised Kathryn would be singing "Let Go the Line" by Max Webster a third higher that the original, so we fired up iVoice.
It worked beautifully, a very useful tool for anyone who might want to hear/practise a song in a key other than the original; in the old days (last month, that is ;-) changing the pitch of a song meant either speeding it up or slowing it down to make it higher/lower.
It does take a little time for the processing (the message reads "Please wait. We are doing our magic."). However, the resulting file can be saved into an archive for later playback.
The app is $1.99; definitely going to get my money's worth out of that one! Perhaps some of you could find a use for it too — check it out here: http://itunes.apple.com/us/app/ivoice/id403483119?mt=8#
... or search 'iVoice" in the iTunes App Store.
p.s. Kathryn did a beautiful job of "Let Go the Line", BTW. :-)