Harmonix weighed in on its own forums, which pegged the DLC as a three track pack instead, including "Adolescents," "Pardon Me," and "Wish You Were Here." The post added, "Not sure where those other two tracks came from (we may be talking with them about licensing them) but they're not part of the pack in August and they're not on the DLC spreadsheet in the near future."
Fans will no doubt be happy to hear the news, as this will (bizarrely) be the first Incubus track pack for a Rock Band title. Previously, only "Drive" was available through Guitar Hero: World Tour., and "Dig" is in Lego Rock Band (exportable). We've reached out to Harmonix for pricing info and release date, but expect it to be around $5.50, given past pricing for three-song track packs.
[Thanks Lewis and Sean!]