How can I merge two iTunes libraries?

It was brought up in this article at TUAW and I responded with my ideas below.

I don’t believe TuneRanger would be a good purchase based on the reviews at several websites like Amazon and Cnet.

9 reviews at Amazon gave it 2 stars (low rating) with the majority giving it 1 star. You can read more here:
http://www.amazon.com/Smith-Micro-Software-Inc-TRHBX2/dp/B0010DG5QY

If you want to do this your best case is to make a case at Apple for it. If you have Applecare then you can legitimately ask how you can accomplish this. If I were to do this I wouldn’t expect to be able to save all the data. I would expect at the very least that 3rd party software would miss things like smart playlists, and metadata.

Try SyncoTunes. It has pretty good reviews.
http://homepage.mac.com/oligrob/syncOtunes/syncOtunes.html
http://forums.macrumors.com/showthread.php?t=473252

Chimac