The Post-Gazette has a good rundown of the roster, which will be set by this afternoon. Here's my best guess about what will happen (and it's just a guess, as there's still a lot of uncertainty here):
-P- John Raynor stays, and Steve Pearce, who has an option, heads back to Indianapolis. The P-G mentions that the Pirates could try to sneak Raynor through waivers and then work out a deal with the Marlins the way they did with Evan Meek a couple years ago, but honestly, I didn't understand why the Rays made that deal for Meek--it seemed like a gift--and I don't see why the Marlins would do that with Raynor unless they got real value.
-P- Hayden Penn also stays despite allowing two runs Saturday, because management likes his stuff and because the Pirates typically go with twelve pitchers rather than eleven.
I wouldn't be surprised to see some sort of kamikaze waiver claim or something, though. If the Pirates do drop Penn, I'd love to see Pearce get that last spot on the bench--he'll at least provide competent pinch hitting, whereas Vazquez doesn't do much of anything.
UPDATE 2:31 PM: Yep. Vazquez goes home, Pearce goes to Indianapolis, and Raynor and Penn make the team. Just to be clear, in case I wasn't above, I have no problem with the Pirates keeping Penn for a while to find out what they've got. He's shown good stuff since arriving, and that's probably much more important than the actual results. He's young enough to become an effective pitcher, and he has very little experience as a reliever, so there might be room for upside just in him becoming used to the role. And as I wrote last week, I'm all about experiments at this stage. As for Pearce and Raynor, I do think it would be nice if Pearce got a chance to become one of the Pirates' top bench players, but at least by keeping Raynor on the big club, they get to keep both guys in the organization, since Raynor is a Rule 5 guy and would probably be lost if he didn't make the team.