Well - MPL is dead, burried and gone.

You're talking about Phoenix, which WAS the 2001 Athena Precursor Mission

"The data coming in from Mars is just starting to be analyzed, and I don't think that at the current time we know enough about Mars to pick out an optimal landing site for MPL."

I'd argue otherwise - Odyssey has sent us superb data regarding possible water-ice deposits in the north polar region - and this is where Phoenix is being targetted. To be honest, an MER would do little good up there. The mission wont last long enough for a rover to get a chance to do much exploring, and the sub-surface ice would be unreachable and essentially un-analysable by an MER.

"We could launch MPL in the next cycle when we have a better idea of exactly where to land it. "

We already know :) North polar region, courtesy of Odyssey, and the area is being mapped with MGS and a final decision will probably be done courtesy of MRO data. Precision landing isnt required, it's fairly safe up there.

Doug