The Twins are keeping things hush-hush. What I've read, it's nothing serious -- it's an inflammation of the sacroiliac. Doesn't sound like it will be a long-term problem. Read that a couple days ago.
Here is the link to the Twins Insider blog. Probably your best source for the Twins: http://blogs2.startribune.com/blogs/neal/
C-Mauer, 1B-Fielder, 2B-Kinsler, SS-Zobrist, 3B-M. Cabrera
OF-Beltran, Markakis, Crawford
UTIL/Bench-Vlad, Damon, J. Reyes
SP-Billingsley, Oswalt, King Felix, Shields, Wandy, Carpenter, Edwin Jackson, B. Webb
RP-Nathan, F. Francisco, B. Wilson, Street