If Apple DOES introduce C2D MacBook Pros at this, it will have to totally redesign the case to make it "invite event" worthy.
If all that's being changed is the processor, or minor cae changes (like the addition of FW800 across the line), it will simply be done in silent, overnight fashion as was the case with the iMac update.
That being said, I don't see such a radical case design this soon. That seems more like something where they'd like to focus on the computer itself, which wouldn't happen as part of a photo show.
Why do people seem convinced Apple won't release something like an SLR or video camera?
Also, there's always a chance that in addition to an Aperture update, we'll get TOTALLY NEW photo software; remember what happened with Final Cut Pro - first came it and then came a slew of other video products from Apple.