I am thinking that the next release of the MBP will use the first gen Penryn chips. Why? Because: A. This MBP has likely been in the works for some time, so was probably developed under the (then state of the art and unreleased) penryn gen 1 chips. And B. Apple can squeeze in more revisions (and hence attract more buyers) by first issuing a MBP with the gen 1 platform, and later in the fall/winter release a new MBP with Montevina.
If Apple waited until June to release a new MBP, they would be behind others (Sony,IBM, etc) by 5-6 months. When you are a top computer manufacturer, you have to keep up with the technology. I don't expect that apple would skip over processors that are perfectly suitable for their products because 'something better is coming out'. (Sound familiar?)