No way.
Think about the PR level vs WWDC. With WWDC, you have thousands of the most hard-core advocates/developers in attendance. Every Wall St analyst who covers the stock will be tuned in for the play-by-play description. Hundreds of thousands more crawling the news/rumor sites. The mainstream media ready to report on breaking developments. D: is a tiny blip on the radar screen in comparison - wire service reporting rather than dedicated reporters from every major news source (conventional or otherwise).
Not that D: won't be interesting. The Q&A format and AAPL-friendly Walt Mossberg being one of the questioners will be a gas. But I wouldn't expect either Jobs or Gates to be trying to one-up each other with product announcements and such. They both have a lot of class and neither wants to make this look like the ultimate "Hello, I'm a Mac. And I'm a PC" commercial (oooh, some YouTube junkie is going to have a blast when the video of this interview becomes available).
Still, we might get lucky, as Walt will no doubt ask questions about the evolution/convergence of notebooks/PDA
s/cell phones etc. and how each company is viewing it. Might actually wrangle a few interesting tidbits out of Jobs in that context. Or perhaps a question about the xBox vs Apple TV approach and where those might lead.