It's not clear what it is, but Pistol Annies are up to something. The all-female country trio featuring Miranda Lambert, Angaleena Presley and Ashley Monroe are just two months removed from releasing their debut album, but already seem to be working on something new.

It's not clear what they're working on, but famed producer T Bone Burnett is involved. "In the studio with T-Bone. Chills, chills, and more chills. Amazing experience," Presley tweeted on Tuesday. Yesterday, someone left this tweet on the official Pistol Annies' Twitter page: "What an unbelievable experience. Thank you T-Bone."

An attached picture shows a sign that reads "Reserved for T-Bone Burnett." Monroe also got in on the Twitter fun. "Leaving the studio with the girls. 2nd day working on a lil treat with Tbone burnett .. Pretty sure I'm having a mini stroke. Too excited," she said yesterday.

Burnett is the Grammy winning producer of the 'O Brother Where Art Though?' soundtrack. He has also worked with dozens of the biggest names in rock and country and overseen the soundtrack to movies like 'Walk the Line' and 'The Big Lebowski.'