...will take place tomorrow in Washington DC:

President Obama will have lunch with his one-time Republican rival, Mitt Romney, at the White House on Thursday, making good on an election-night pledge by the president to meet with Mr. Romney.

The White House announced the event Wednesday, in a statement released by Mr. Obama’s press secretary. The lunch will take place in the Private Dining Room, next to the Oval Office in the West Wing, the White House said.
“It will be the first opportunity they have had to visit since the election,” the statement says. “There will be no press coverage of the meeting.”

Knowing how much Romney hates it when the government hands out free lunches as gifts, I certainly hope he'll brown bag it. Romney will also meet with Paul Ryan before the lunch, which will be the first time the two men have talked since Election Day. I imagine tomorrow will be the most awkward day in Mitt Romney's already incredibly awkward life.