Dan Aykroyd has confirmed on his Twitter feed that he's been on the set shooting a cameo appearance.

"Shooting my scene with funny, beautiful Kristen Wiig," said Aykroyd. "Lady Ghostbusters are adorable, hilarious and badass! Exhilarating!" It'd be lovely to think he showed up as Ray Stantz, but some rumourmongers believe he's just playing a cab driver: his presence a simple wink to the audience. Aykroyd has since deleted the tweet, but the ghost was already out of the trap.

Paul Feig has so far been keeping many of the details about the new movie close to his chest, but we do know that the basic story, written by the director and The Heat’s Katie Dippold finds Wiig and McCarthy as a pair of unheralded authors who write a book positing that ghosts are real. Flash forward a few years and Wiig lands a prestigious teaching position at Columbia University. Which is great, until her book resurfaces and she is laughed out of academia. Wiig reunites with McCarthy and the other two proton pack-packing phantom wranglers, and she gets some sweet revenge when ghosts invade Manhattan.

Source: Press Release