Sebi is the process of a trading interface overhaul. I'm not sure on the timetable for the update, but it shouldn't be too far off as he provided a preview of how the next interface will operate here in the forums.
That being said, it will still show up if you load another user's profile, showing you the overlap between your respective trade and wishlists. It's a bit tedious for the time being, but it's easy enough to find a card you're after, load it's page, and start looking through the people with it in their tradelists.