This is pretty half-baked, but consider the following proposition:

(1) January 9, 2008 is present.

I think it is a vague matter whether or not this is true. Imagine the minutes are slowly ticking away on January 8. It's 11:59. As the time passes, January 9 will be determinately present, but exactly when that happens seems to be a vague matter.

This, however, will lend some support to A-Theory (and either presentism or some version of the moving spotlight view in the ontology of time). For imagine if B-Theory is true. If B-Theory is true, then 'present' functions like an indexical, and (1) really expresses something like the following proposition.

(1*) October 4, 2006 is October 4, 2006.

(1*) is not vague. At least many philosophers are inclined to accept that identity statements are not vague, and whatever motivates us to accept that should motivate us to accept that (1*) is not vague.