Hmm I can't remember if they have ever had an entire band on the show as guests. Anything can happen but I would be VERY VERY VERY surprised to see the Richie, Tico, and Dave playing up there with the kids on Idol. In five years i have never seen that happen. Rickey Minor and the Idol house band has always played the instrumental music no matter who the guest star was or what genre of music. But we'll have to wait and see but like i said i would be kind of shocked to see that happen.
When I said that Jon might sing with them (the contestants) I meant the second night on the results show. The first night (Tuesday) will be just the contestants performing. Sometimes the guest singer does perform with the kids, other times the guest sings alone. Like one year Barry Manilow came out and sang with everyone. I think Gloria Estefan did too. Looks like that blog says the band will be doing the single though so they'll be performing alone.
This season (Diana Ross) (and last season - Queen, Rod Stewart, etc.) the guests are just coaching and helping the kids pick the songs. They haven't had any special guests actually judging since season three (except for at the tryout cities).
Sorry, i'm a little obsessed with the show. It's kind of scary....
