I dont think there is a rush to sell ipad 1 at this time. Maybe a few idiots, but not the majority. Even the fanboys that have half a brain will at least wait a bit longer to migrate from 1 to 2 at reasonable prices. Then there is the rational and sensible ipad 1 owners who can see that the ipad 2 is clearly not a big upgrade and will probably not upgrade at all and just wait for ipad 3.
If you dont have an ipad at all now, an ipad 2 may be attractive. If you already have an ipad 1, I think it is questionable whether an upgrade is worthwhile.