1) One of the bajillion threads on the subject shows the guts of the macbook and why getting a FW plug in would have been difficult (i.e., drop something else). The iMac doesn't have that limited space.
2) The rumor suggests only speedbumps, which means no case redesign. Why would they drop a FW port just on a speed bump?
3) That said, if they introduce new ones w/o FW, I'm jumping on a refurb immediately.
I agree that the next iMacs may only involve a minor speed bump, but the writing is on the wall. FW is slowly being phased out in favor of USB, on the consumer Macs. I'm sure Apple would love to sell more MP's and the more powerful these recent iMacs have become, the less need one has for the MP's, unless you do heavy graphics or CPU intensive work.