Maybe I've solved this, or maybe it's a dumb idea - let me know. One of the things that seems to be a problem for a lot of people on the forums is being stuck with their long-established iTunes store email account and a newer @me/whatever email account. Why couldn't you just use your new email account to set up new iTunes store and iTunes Match accounts, and then add the songs back up under the new account?
Actually you can share your apps and other purchases to any other account (up to 5 I believe) using Home Sharing. The only downside was that app updates required you to enter the password of the original account. However, reports from iOS6 Beta are that you no longer need to do that for updates so this might be a seamless way of handling it.
That is not true at all. If you have Home Sharing set up, you can drag and drop iOS apps from one person's account to another. It is no different than it is with music, tv shows, movies, books, etc. Two people with completely different Apple ID's set for iTunes can share purchases. It is probably one of the most little known things about iOS.
So, to clarify, I can purchase a $20 app then share it with anyone else in my household with different accounts?
Good to know, thanks. Now, off to pick a bone with Apple after telling me I couldn't share the $30 Golfshot app I bought with my father and purchased it twice...