Well, I think it depends on whether it's actually going through or not - that is, it depends on where you are in the process.
I know that Dreamhost requires email verification from the contact email address at Yahoo. Did you do that already? Also, does Yahoo still think that it is your registrar for that domain? If so, maybe you can just lock the domain and prevent the transfer from occurring.
I do know that if you do think that the transfer request is going to fail, Dreamhost can cancel their side of the failed transfer to allow you to initiate it again. I've had to do that at least once.
BTW, it's too late now but you should really start your own thread rather than just using someone else's thread for your questions. It makes it easier for everyone - both the OP, the responders, and everyone else who has to read the whole thread only to figure out that there's a new topic/question at the end unrelated to the original thread. I know that your thread is about domain transfer, but people don't need to read the whole thread in order to understand your question. It's no biggie so don't panic, but I thought I'd try to provide some advice for the future!
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