One has to assume Obama wouldn’t have appointed Sonia Sotomayor without some indication that she’s pro-choice but — based on very, very little information — I wonder if she might not end up being an abortion centrist.

First, in Center for Reproductive Law and Policy v. Bush, she actually ruled against the pro-choice group on Constitutional grounds.
Second, in Amnesty America v. Town of West Hartford, she ruled in favor of the rights of anti-abortion protestors.
Neither of these cases dealt with the merits of abortion. Nonetheless, it’s interesting that in the two cases we know of that related partly to abortion, she took the position that pro-life groups would have wanted (albeit for reasons unrelated to Roe v. Wade). At a minimum, these cases would seem to indicate that, if she is pro-choice, she didn’t let those views affect her view of the relevant law.
Third, though we certainly can’t generalize, it is the case that Hispanics are the most pro-life members of the Democratic coalition. In Beliefnet’s “12 Tribes” study conducted in the summer of 2008, 58.9% wanted strong restrictions on abortion, while 41.1% took the pro-choice position. She may well be in the 41.1% but at a minimum she grew up in an environment where the pro-life position was well-respected.
I realize this is thin gruel, and new information might turn up any second showing her strong pro-choice position but I’m based on what we know now I’m not sure we can assume she’s hard-line pro-choicer.
UPDATE: Interestingly, Americans United for Life has issued their statement opposing Sotomayor — but it lists no specific pro-choice comments or rulings from the judge. Instead, they focus on her general judicial philosophy: “She believes the role of the Court is to set policy which is exactly the philosophy that led to the Supreme Court turning into the National Abortion Control Board.”
UPDATE #2: The White House briefing also points to her ruling in Lin v Gonzales in which she ruled in favor of a Chinese woman who sought asylum in part because of the force sterilization and abortion policies of the Chinese government.
UPDATE #3: She reportedly was on the baord of a group formerly called the Maternity Center Association, now called Childbirth Connect. They list “20 Rights of Childbearing Women.” None of them relate to the “right to choose.” In fact, I find no mention of abortion on their website.
UPDATE #4: Nancy Keenan, the head of NARAL, the leading pro-choice group, praised her accomplishments but had no sense of whether Sotomayor is pro-choice: “We look forward to learning more about Judge Sotomayor’s views on the right to privacy and the landmark Roe v. Wade decision as the Senate’s hearing process moves forward.”