Update: No surprise, but Coachella has officially confirmed that Interpol are playing on April 15th.
In a new interview, Sam lets it slip that the band will be playing the Coachella festival in April 2011. Here's the translation of that part:
AA - Any visit to Mexico City?
Sam - Yeah, maybe. We will have to see what happens after April. What we have planned. Because there will be Coachella.. ahm. No, nevermind, ahahah, I didn't say that. But yeah we will return.