Let the show begin

Asif Ali Zardari is president because the US leaned on Musharraf to grant him and his wife (and many others) amnesty from corruption charges through a presidential directive called the National Reconciliation Ordinance. The legality of the NRO has always been in question. No more it seems as the Pakistan Supreme Court has just declared it unconstitutional.
Pakistan's Supreme Court declared on Wednesday that an amnesty that had protected politicians, including President Asif Ali Zardari, from corruption and criminal charges, was unconstitutional.

The 17-judge court invalidated the National Reconciliation Order, saying in its ruling that the amnesty "seems to be against the national interest" and "violates various provisions of the Constitution."

...

The supreme court said its ruling revived all cases that had been suspended or withdrawn under the amnesty.

Zardari still has immunity due to his role as president. But many of his supporters do not. Look for lots of negotiations.