Clinton:
Clinton was impeached because he used his position to subvert a legal case(Paula Jones). He later, he used his position to try to do the same with Lewinski. All that the media seemed to pick up was the sex aspect (who really cares?.. I guess the media is locked onto ‘sex sells’). Clinton Impeachment
Gingrich:
Admitted it fairly quickly when discovered, instead of trying to redefine what the meaning of the word ‘is’ is.. His wife may make him pay more than the any court/media scandal.
The difference is very simply that we are a country of laws. Gingrich having an affair made him a philanderer(part time/full time?), but that was not illegal. Clinton was also a philanderer as a result of (Paula Jones/Monica Lewinski). Philandering is not illegal (though the extreme right would want to make it a felony). It is what each did afterwards that sets them apart.
As for Libby. I am concerned if he would be pardoned. It would set a bad precedent, though in a way that precedent has already been set (look at pardons of other presidents as they leave office). This doesn’t make it right though.