To understand the implications of Benazir Bhutto's assassination for Pakistan, first imagine what that country would look like without her Pakistan People's party. It has been overwhelmingly a dynastic party and she was the last politically viable representative of the Bhutto dynasty. Without her to hold it together, it is highly probable the PPP will disintegrate.
In the short term, this is likely to benefit President Pervez Musharraf and the army but, in the longer term, Islamist extremists may have the most to gain.