A little Googling found out that Noah Wyle will be back next year. It also shed light on what's going on with Dr. Galant.
Apparently, Sharif Atkins was in a failed pilot from Wells Productions, the folks responsible for ER. To keep him around, they signed him to a temporary contract for a few episodes and later decided to keep him around for the longer term.
Well, he's just been off shooting a pilot for another possible NBC series, "Hawaii". So if the pilot makes it to the schedule, we'll probably not see much more of Galant around the ER. If not, we will.
And if we do, it'd be nice if they find some more for him to do. (I'd like to see a bit more of Corday too, other than the "Many Loves of Elizabeth Corday" segments they've been doing...)