I'm afraid you will be vastly disappointed until the imminent hardware refresh following Leopard. I don't think this will happen until Oct/Nov or perhaps even Jan.
MBP's will definetely not be refreshed again this year. Even 2008-january is not likely as it would give this tomorrow-to-be-released MBP line only 6 month life cycle. April is more likely, and then we could always hope getting a case redesign with Penryn inside.
If this coming MBP refresh is mind blowing, then it's definetely the last Aluminum revision next one likely has a new case.