Yup... There is a bit of discussion about this one in the forum. What happened is when they were building the orginial catalog they included items besides CDs in the listing, i.e. Vinyl, Cassettes, etc, which they now need to weed out.
For me a couple of items on my want list were deprecated like the Keene Brothers which I found replacement for. I lost a couple singles and imports requests but nothing significant. Same for my have list and none of the items would have been traded anyways.
Of course they also managed to create a bit of sticky messy by opening up their database for multiple listings of the same album if they have different UPCs. For instance there are two versions of the new Bob Dylan CD one which can bought via the store the other not. This of course means you'd have to request both enteries and hope they don't get shipped at the same time. However, I seriously doubt anyone will be trading that one anytime soon. The Paris Hilton CD on the other hand...