There have been some rumblings about moving Pedroia back to shortstop. This would be a bit unusual, as players typically move to easier positions as they age. Bill James came up with the idea of the defensive spectrum in his 1982 Baseball Abstract, and it works something like this:
Essentially the idea is that players on the left side of the spectrum require the least amount of defensive ability, but are expected to carry the offense. You could throw DH on there on the left side, if you'd like. Craig Biggio had perhaps the most interesting movement across the spectrum, starting at catcher, moving to second base, then center field and left field, before returning to second base.
Pedroia is an above average second baseman (UZR/150 10.6 in 2009 and 10.5 in 2008) and the cost to shift from second base to shortstop is considered to be somewhere around 10 runs, so the numbers indicate he could be an average defensive shortstop. Offensively, a replacement level shortstop is about 7 runs worse than the replacement level second basemen, so this wouldn't change Pedroia's overall value to the team, but would give them more flexibility in the free agent or trade market. Pedroia played shortstop at Arizona State (bumping Ian Kinsler from the starting lineup, who later transferred to Missouri), so shortstop isn't something completely new. Pedroia even played shortstop throughout the minors, making more appearances there than at 2B in 2006, his last year at AAA. Last year Alexei Ramirez shifted from second base to shortstop and his UZR/150 improved from -10.6 to 2.4. Shortstop was Alexei's natural position and he had basically be thrown in at second base in 2008, so it isn't a perfect comparison.
The one knock against this move is that Pedroia was moved off of short for a reason. Coming up through the minors his arm strength was questionable for the position, especially when making throws from the hole. However, his minor league defensive error totals are spectacular (only 7, as Gammons points out), so if arm strength isn't an issue it could be a nice move for the Sox. Another important point Gammons makes is that this would likely be a short term move, as Jose Iglesias, the 19 year old Cuban shortstop, is supposed to be a spectacular defender.