Core 2 Duo (Merom) will probably arrive in force in September or so. But if you're getting the notebook for college or university, get a MacBook Pro now. Familiarize yourself with the system and make sure you've got a reliable unit <i>before</i> you start classes. And besides, you can take advantage of Apple's "free" iPod promo.
If you're not in school, get a MacBook Pro only if you need a notebook right away. When you're purchasing "just because" you want to get the best unit you can for the money.