An article on rockbandaide.com shows a tweet from Incubus's manager that five of the band's songs are coming to Rock Band in August. Those songs would be, well, the five you'd expect:

• Adolescents
• Megalomaniac
• Pardon Me
• Stellar
• Wish You Were Here

This is still a rumor, but it's specific and coming from a credible source. It's likely that this is true.

There's no word on pricing or pro charts, but I'd expect a 5-pack with standard prices and pro upgrades on about half of the songs. I'm glad to have "Stellar" come back, because I'm a sucker for repaying for Guitar Hero songs. As a passing Incubus fan, I'm glad to see them get some more tracks and I'm really happy that they picked well known songs. No doubt they have better deeper tracks, but I think it's a good call to pick something that most people would know.

YES! One of my favorite bands, easily (at least for their older stuff, don't care at all for their newest music). 
 
Terrible song choices, though. I can live with Megalomaniac, and maybe Wish You Were Here, but I'm so sick of the most well known songs being picked (surprised that Drive isn't on there). Seriously, give me some SCIENCE, Make Yourself that isn't Pardon Me, and something else from ACLofM. 
 
My five choices would have been Deep Inside, New Skin, Beware! Criminal, ACLotM, and When It Comes.

update to OP: HMX replied and said it'll be a 3-pack of Adolescents, Wish You Were Here, and Pardon Me. Stellar and Megalomaniac won't be involved.

Pardon me?

Ugh...I hate Adolescents, and if it's what the rest of the new album sounds like (haven't listened to it yet), then Incubus is done in my eyes. Wish You Were Here is a good song, but I can't imagine it'll be all that fun in Rock Band, at least compared to many of the band's other songs. And Pardon Me...even as a die hard Incubus fan, I honestly think that is one of their worst songs.

@Hobbies: I wanted them to include "Privilege" I love the intro to that song.