They're not getting laid off by a startup now they're getting laid off by Google. They likely get a severance. In CA at least if they're laying off a significant portion it's cosidered a plant closing which should give everyone about 6 months severance.
This all comes from someone who left Meebo recently and is still close with people that work there.
Not sure exactly how many, but it sounds like it was a good number.
Note: I said it was the majority, that's what my friend made it sound like, but I'm not sure.. will update once I find out