Fox News is reporting that John Roberts of the Court of Appeals for the D.C. Circuit will be President Bush's pick to replace Justice O'Connor on the SCOTUS.
There is an interesting precedent set by Sen. Orrin Hatch (R, UT) during the appointments of Ruth Bader-Ginsberg (former lawyer for the ACLU) and Justice Breyer by President Clinton. Although the appointees were at the other end of the philosophical spectrum of the Senator (and a great many other Senators), both were overwhelming approved by the Senate. Justice Bader-Ginsberg received a 99-0 vote for her confirmation.
Here is the DOJ bio for Roberts. And here is a Law.Com article about the presumptive nominee. (H/T to ConfirmThem.)
Congressional Quarterly has a good summary of the confirmation process and history.