Some trenchant thoughts on the significance of Hillary's! unsecured email usage as SOS from Sean Linnane:

Hillary Clinton is full of crap, and I'm being polite. Consider: she set up a personal server and created her own e-mail address, using it for private AND official State Department use. From a SIGINT perspective, the Secretary of State is a High Value Target - not for destruction but for electronic surveillance and collection. The collection is conducted not only by hostile governments, but by friendly ones as well - our allies spy on us, and vice versa. Long before she took the job - probably when she was occupying the White House with Bill Clinton - collection against her began. She must think that her server is more secure than that of the DOS. Government agencies' electronic communications are always being targeted for "hacking" but more often, they are monitored for message traffic. Information is gathered via electronic monitoring. Hacking is more akin to an act of sabotage. Some technician who serviced the server in her home was probably bribed, blackmailed or otherwise coerced by an interested foreign intelligence service for the purpose of gaining access to the Clintons' in-home server.

U.S. "dot gov" e-mail services are monitored by U.S. government employees whose job is to watch for classified "leaks" (AKA "spillage"). Was Hillary concerned that the Communications Security (COMSEC) monitors might find out something about her attitudes, behaviors, and opinions that might get out to the public? By law, COMSEC monitors are prohibited from tapping into private e-mails.

If anyone thinks that Hillary Rodham Clinton sent 50,000 e-mails in four years and there wasn't an increased risk of "spillage" they are smoking dogfood (I won't say if they are inhaling or not). No doubt she spilled a lot. She was handing information to our enemies, and the NSA COMSEC guys were likely going berserk. Others have been fired for less. 

Go thee forth and read it all.

And the best comment over at Ace's so far:

20 Clinton's new line of defense: 

"As a woman, I send fe-mails, not emails. So it's true I never sent a classified email, you sexists!!!"