Sorry Spice Girls: R.E.M. just one-upped you in the "most exciting concert of 2008" department. The band, which famously played a free concert for 20,000 fans here in May 2001, announced Monday afternoon that their new tour (in support of their new album Accelerate) will feature both The National and Modest Mouse. All three bands are indisputable headliners, and it's a fantastic combination: R.E.M. are old and established, with something to prove after 2004's pretty-good-but-not-great......