Pay no attention to that man behind the curtain

From Strategy Page:

Egypt Quietly Invades Libya
The rebellion against the Kadaffi dictatorship in Libya has not produced any official outside help, but Egypt has apparently sent some of its commandos in to help out the largely amateur rebel force. Wearing civilian clothes, the hundred or so Egyptian commandos are officially not there, but are providing crucial skills and experience to help the rebels cope with the largely irregular, and mercenary, force still controlled by the Kadaffi clan. There are also some commandos from Britain (SAS) and American (Special Forces) operators are also believed wandering around, mainly to escort diplomats or perform reconnaissance (and find out who is in charge among the rebels).

But a note of caution:

Any Egyptian involvement in Libya has to be handled very carefully. While the two countries fought a three day war in 1977, the real cause of tension is the fact that for thousands of years, most of Libya was considered part of Egypt. Given the fact that Libya has all that oil, and less than a tenth of the population of Egypt, well, then, you can figure out the rest. But for the moment, everyone is a revolutionary brother. At least for as long as the moment lasts, then history takes over.

Boundaries in the Middle East are not geographical, they are familial first and tribal second.