Judge Alito, a new Souter?
How's that for a provocative title?
First, I am not too terribly familiar with the newest victim in the nomination process. I have no idea how he scores with the business community so I have no idea if this is a serious nomination or a distraction. If he was on the Chamber of Commerce's short list, then Bush will fight for him and he will be confirmed. If he was not, this is likely an expendible nomination designed to shore up the President's base - although this may be the lack act of a desparate President (since if the nuclear option is invoked the rest of the legislative session is done and the next one too). Then the nomination to look out for is the next one.
Second, I have no knowledge that he is secretly pro-choice. I have only statistics to use as prediction. Since Roe was decided, 66% of Republican nominees have affirmed Roe (Stevens, Kennedy, Souter and O'Connor) while Thomas and Scalia have sought to overturn it. Both Democrats supported Roe. The late Chief was already on the Court when Roe was decided and was against it. Given those odds, it is likely that either Alito or Roberts will vote to affirm Roe when it comes up again - if not both. Of course, even if they are both anti-Roe, that is still only four votes. I would expect Roberts to either affirm Roe or come up with some compromise which is unanimous.
Of course, a true originalist would have to look long and hard to find protection for the unborn at the founding of the constitution or even the ratification of the Fourteenth Amendment. Anti-abortion laws were a more recent invention and protection of the unborn cannot be found anywhere in the text, which if read explictly would seem to prevent it since to be considered a citizen under the constitution you must be born or naturalized.