This time around, they've got a good short analysis up of what might happen to green BoEs in Wrath of the Lich King. Once upon a time, there was actually a good market for BoEs on the AH -- some of them even challenged Karazhan gear in the early days of level 70, so anyone new to 70 could just spend some time in the Auction House and pick up some nice gear for running the basic instances and starting to build up blues and epics. But in my experience the market has thinned out lately -- while there's always a market for enchanging materials you can get from BoEs, people aren't that interested in buying green gear with epics so easy to get elsewhere. Most of the time, I get more from vendors for greens than I can actually sell them for on the AH.
But WoW Econ says there's a bump on the way -- Death Knights are going to be shooting through 60-70 directly after Wrath, and they're going to want the level 66-70 greens floating around (plate gear with Strength and Stam on it), so that will probably sell well. But everything else is pretty much dried up -- DE it if you can, or just vendor it away and move on. The gold will come quicker in Northrend anyway.