Just read the latest Ultimates, and the final two pages several times.

So who is the mystery member of the team drinking coffee with Pym?

Tony? Don't buy it - he turned on Thor...and he really LIKED Thor.

Hawkeye? Don't think so. His character doesn't seem shaped to where he'd be friendly with Pym, let alone familiar.

Pietro? If Hawkeye would be distant, Quicksilver would be on another continent.

Jarvis? I know he isn't an "official" member, but he seems in on everything, and the way the dialogue comes out you could almost see it, except Jarvis likes to push the hyperbole and innuendo especially.

So what does that leave us?

I think it is a woman.

I think Wanda is out. Hank was pretty much gone by the time she was officially on board.

Black Widow? Same deal, and she doesn't seem nay more inclined to be friendly as Hawkeye - and the reasoning offered doesn't mesh with her origins (same with Wanda.)

Process of elimination:

Dammit!

It's Janet!

Think about it.