Mid-career federal government lawyers in an expensive city make $130k a year. Class action attorneys generally get a significant fraction of the value of the settlement. And the value of the settlement is calculated in kind of a crazy way particularly when it comes to injunctive relief.
In the google buzz case, which resulted in no monetary relief to the class in general (representative plaintiffs were given a small award, the rest was cy pres) class plaintiffs were awarded over $2.1M plus expenses for 2550 billable hours* over the course of a calendar year.
*That's a little understated because the filing that number came from was near the end of the litigation, but not at the very end.