My colleague Marc Ambinder has a useful post about the State Dinner crashers episode. Agree with him that this is all a little silly. It's a breach of security worth investigating, but it's more interesting because of the light it shines on the idiocy of reality TV than on presidential safety, which was never in any remote danger.
Wanted to add an historical footnote. The Secret Service's Uniformed Division, which secures the White House perimeter, is a relatively recent invention. It only got its name in 1977, and it came about in the 1970s to cover both the White House and diplomatic missions. Its patrol cars are ubiquitous around Washington's Embassy Row. Formed in 1970, the division was a result of all the protests around the Vietnam War and an interest in beefing up embassy security, which had heretofore been left up to the D.C. police. Nixon, in a Nixonian touch, wanted to give them regal uniforms before he was wisely talked out of it. Now they dress like police with white shirts. Before then, white House security had been a mix of the military, the regular Secret Service and D.C. police.
The guys in the division tend to be unfailingly polite and work well with their better known agent brethren. I admire them, although some years ago I wrote a piece arguing that the embassy policing ought to be given back to the D.C. force because Washington's best cops were winding up patrolling its safest neighborhoods. If I can ever find the piece, written for The Washington Monthly, I'll post it.
Washington is, by the way, served by a crazy quilt of police forces including the D.C. police, the Uniformed Division of the Secret Service, the Park Police, a General Services Administration force and even a Smithsonian police force that patrols the National Zoo. The Mint has its own force, and the Capitol Police patrols the Capitol and surrounding areas. The Metro system has its own police force. The best link on all the forces is here.
I wouldn't argue for consolidation, but the number of different forces that can arrest you is remarkable.