Well, Rossman (who has sold a lot of these) has said that Dell says they're not supposed to transfer the warranty. However, I sold a 2405FPW recently and they had no trouble transferring the warranty to the new owner. Other people have been able to do it fairly easily as well.
There is one thing to note though. A lot of people claim these monitors have 3 year warranties, and even Dell's website and documentation states it so. However, the person I sold the monitor to, was told by Dell that their monitors only carry a one year warranty. I don't know if perhaps this is a shady practice or a misinformed CSR.