As Josh just observed, Rep. Jerry Lewis (R-CA) is still under investigation for his role in alleged trading of congressional earmarks. A major figure in that inquiry, which you can read more about here, is GOP congressman-turned-lobbyist Bill Lowery.
Lowery's lawyer during the initial days of the Lewis probe, and during the height of the Randy "Duke" Cunningham scandal, was former Clinton administration counsel Lanny Breuer -- who was recently nominated by President Obama to lead the Justice Department's criminal division.
Breuer was also a registered lobbyist as recently as last year, representing Yahoo on "law enforcement demands for user information," according to the Senate disclosure database.
Does that mean Breuer will have to seek a waiver from the Obama administration's ethics order on prior lobbying, as Pentagon No. 2 nominee Bill Lynn recently did? Perhaps, though his was a far narrower involvement than that of Lynn or former Goldman Sachs lobbyist Mark Patterson, the new Treasury Department chief of staff.
Either way, it's worth noting that private sector employment isn't an automatic black mark for those re-entering government service.