It's been sorted out. Frank Mir will face Brock Lesnar at UFC 100 for the unified Heavyweight Title. Meanwhile, Rashad Evans will put his Light Heavyweight Title on the line against Rampage Jackson (or Machida, if Rampage can't make the quick turnaround) at UFC 98. The announcements were made during the UFC 96 PPV.
I'm glad the UFC did it this way. They really had no choice because they were selling UFC 98 as a major event. You gotta give the fans who already paid high prices for tickets a big time fight. Evans/Jackson definitely is a suitable replacement. There is also some added drama with the intense staredown the two had after the Jardine fight.
The staredown was like watching two drunk guys wrestling. It starts out innocent then a couple minutes later punches are flying. Rampage actually deserves some credit for diffusing the situation. He walked away when he noticed Evans was getting pissed. They were about thirty seconds away from someone pushing the other then a riot would have broken out. It would have been funny to see Bruce Buffer's reaction. I imagine he'd climb over the cage like a gecko then unceremoniously fall to the floor before dusting off his suit and declaring, "I've never felt better!"