There had been some speculation that he would be buried in Poland...
From Tampa Bay Online:
Pope John Paul II's funeral will be held Friday morning, and his remains will be interred in the grotto of St. Peter's Basilica where pontiffs throughout the ages have been laid to rest, the Vatican said Monday.
Chief spokesman Joaquin Navarro-Valls made the announcement after the College of Cardinals met for 2 1/2 hours in its first gathering since the pope's death and ahead of a secret vote later this month to elect a successor to John Paul.
Navarro-Valls said the basilica would remain open overnight except for three hours for cleaning every night this week to accommodate the thousands of mourners.