The homepage of modestmouse.com seems to have been replaced with an image of static. The rest of the old site is still there if you hit any of the old links. Could be an indication of a new site coming soon.
Something else that has come up today, but doesn't seem to have been confirmed yet; Rock City in Nottingham has posted this on their Facebook page:
Modest Mouse: "After much thought, we have decided to cancel our EU/UK tour to continue work on our forthcoming album. We do appreciate our fans and promise that we will make it up to you next year.
Refunds will be available at the point of purchase.
We look forward to sharing our new music with the world next year."
So far they're the only one announcing this. With Europe only waking up in a few hours, we're hoping to start get official word from the other venues and festivals.