|Once a registration has been transferred to DreamHost successfully, your old registrar cannot reclaim the registration without you explicitly approving a transfer back to them.
Unfortunately, getting the registration to transfer away from a registrar in the first place can be a bit more challenging.
Often, registrar's have a "lock" setting which they claim is to prevent unauthorized transfers of domains away from them. You'll have to contact your current registrar to figure out how to unlock your domain if they've locked it for you. It may be tricky, especially if you don't have access to your contact email address anymore.
Also, sometimes domains that aren't locked still just mysteriously fail to be approved away from the current registrar. Network Solutions/verisign is especially notorious for this. If this happens, the only thing to really do is try and re-try to transfer the domain from them, and to try and contact them about it. Unfortunately, registrars can be very unresponsive when it comes to outgoing transfers. :(
Last updated: Dec 13, 2002.