Tipler's Omega Point occurs when the processing capability effectively becomes infinite, as the processors will be able to simulate every possible future before the universe ends - a state also known as "Aleph".
Within this environment, Tipler imagines that intelligent beings, human personalities, will be run as simulations within the system. As a result, after the Omega Point, humans will have omnipotence, able to see all of history and predict all of the future. Additionally, as all history becomes available, past personalities will be able to run as well. Within the simulation, this appears to be the dead rising
Tipler's books are very interesting and he makes a great case for future simulations, in space travel and eventually universal simulated histories. After all, your skeleton may be a simulation itself.