Updated

After years of sniping and bitter competition, "Dancing With the Stars" and "American Idol" are suddenly great friends.

Tomorrow night, Pia Toscano -- who made waves when she was surprisingly voted off "Idol" earlier this month -- will sing on "DWTS" while dancers Mark Ballas and Karina Smirnoff boogie on stage.

Just last week, Ryan Seacrest waded out into the "Idol" audience to chat up Ballas about his new favorite "Idol" -- now that his reported new squeeze, Pia, is out of the running.

HOT SHOTS: Pia Toscano.

Pia's appearance is the culmination of weeks of subtle good vibes the two shows have -- uncharacteristically -- been sending out to each other, starting with "DWTS" showcasing "Idol" judge Jennifer Lopez's latest hit "On the Floor" for a show-opening number last month.

That would not have happened last year, when Simon Cowell was sneering on "Idol": "If you listen to one of those dancing shows, they always have a singer murdering a song on it."

And when "DWTS" topped "Idol" in the ratings for a few weeks last spring, "DWTS" host Tom Bergeron bragged in an interview that he got "a kick out of the fact that it's probably making them a little crazy."

So, what happened? Why all of a sudden are the two shows -- which rank No. 1 and 2 in the ratings and air on competing networks -- suddenly BFFs?

For the record, the people who run the two shows say they've always been friends.

"There's no skullduggery," says "DWTS" Executive Producer Conrad Green.

"She was a huge story on 'American Idol' this season," he says of the Pia invitation. "She's also very close to Mark, so we thought it would be nice to see her again and to get Mark to dance to her.

"We want to bring people onto the show that people want to watch. It's that simple. If they happen to be on the other massive reality show, then that's great."

Go to NYPost.com for the full report.