re: Someone said it would take a significantly heavier launch vehicle in '09.
That ws me :)
It took a Delta II Heavy to chuck Opportunity in '03 - supposedly the most favorable launch opportunity in 60,000 years (blah blah)
Options would be something like two on an Atlas V or Delta IV perhaps.
'05 is MRO, '07 is Phoenix, '09 is Telecom Orbiter (and possible MSL).... one mission per slot makes sense to me.
Doug