If you haven't heard about Songsmith (Link) by now, it's a Microsoft project where users can essentially sing a vocal track and the software makes up a backing track based on some parameters you set. (Here's their (really bad) video explaining the whole thing if you want to quickly get up to speed).
I remember watching that thinking how cool it would be for someone like my 8yr. old daughter who loves to go around the house singing, making up the words as she goes. It's a very neat concept.
But... it's certainly no replacement for real songwriting as you can see by the many hilarious videos flooding into YouTube right now... I don't think this is what the developers had in mind.
Watch a bit from each one for a good laugh.
Roxanne
Eye of the Tiger
Running with the Devil
Enter Sandman
Crazy Train
There's tons more on YouTube and I expect thousands more to come. LOL!