Terry Doyle is a 26-year old right-hander who hasn't pitched above double-A. He has good control (2.0 BB/9 in 100 career double-A innings), keeps base runners to a minimum (1.13 WHIP at double-A), but his strikeout rates haven't been as strong (down to 6.6 K/9).
Can Doyle remain on the active roster all season, in order to avoid being returned to the White Sox? My guess is no. His cutter, effective at inducing ground balls, hasn't been good enough to get him to triple-A. He's been compared to Mark Buehrle for pace, but again, MLB-type comparisons are nice but mean little. (Hat tip to Parker Hageman for the twitter links. He's worth a follow, folks.)
In the minor league phase, the Twins selected Marty Popham from the Indians' system. Popham is 24, and was drafted in the 20th round of the 2008 draft. He's actually made two brief stints at triple-A (totalling just 5.2 innings) where he struck out four and walked four. He has recorded less than 20 innings at double-A.