In about fifteen minutes, Bush is expected to nominate White House Counsel Harriet Miers to fill the O'Connor seat. I don't know much about Miers' judicial ideology (nor does anyone else because she's never been a judge), so I can't really comment on whether Bush made a good choice and followed through on his promise to move the Court to the right.
But from what I can tell, this pick might unify Democrats and Republics in opposition. The Republicans might be upset because her record is nonexistent, and there's little guarantee that she won't be another Souter. The Democrats want assurances that the nominee won't overturn Roe and there's no way to ascertain her view of Roe from a judicial perspective. They will also oppose her because she's perceived as a Bush lackey. So this pick will not make confirmation easier, although I don't see the Democrats mounting a filibuster.
More on this later (although not much more with Rosh Hashanah coming up).
Update: David Bernstein gives what seems to be the only rational reason for choosing Miers (with the exception of cronyism). Like FDR choosing justices to uphold the New Deal, Bush chose justices who will allow him to fight the war on terror, which is his presidential centerpiece. Both Roberts and Miers have extensive experience in the Executive branch and are somewhat more likely than the other justices to defer to the President's war powers.
Todd Zywicki notes that Miers might have to recuse herself in such cases. If that's the case, then the pick was a total waste. But in my mind choosing a justice because he/she will support the President's positions on the war on terror is just wrong. This was a bad pick and there's no other way to slice it.