Vote total update (maybe): If, as a senate source heard below, there are only 55 pledged votes in favor of cloture, and, as Geraghty hears, there may be 33-35 against cloture, are there about 10 votes in play?
If there are 10 in play, these twelve senators may be amongst them according to some Hill sources:

Bond (R-Mo.), Bingaman (D-N.M.), Burr (R-N.C.), Boxer (D-Calif.), Cochran (R-Miss.), Conrad (D-N.D.), Ensign (R-Nev.), Levin (D-Mich.), Gregg (R-N.H.), Nelson (D-Neb.), Hatch (R-Utah), Webb (D-Va.).

Though I think that Gregg is only in so much play: he says he'll vote in favor of proceeding to the bill (i.e. against cloture).