Wired's Noah Shachtman has the goods:

For years, the military has been warning that soldiers' blogs could pose a security threat by leaking sensitive wartime information. But a series of online audits, conducted by the Army, suggests that official Defense Department websites post material that's far more potentially harmful than blogs do.

The audits, performed by the Army Web Risk Assessment Cell between January 2006 and January 2007, found at least 1,813 violations of operational security policy on 878 official military websites. In contrast, the 10-man, Manassas, Virginia, unit discovered 28 breaches, at most, on 594 individual blogs during the same period.

The difference may be that soldiers blogging in combat zones are instinctively more careful than the desk jockeys back in Washington. As Army spokesman Gordon Vlan Veet put it:

Often these bloggers are stationed in the combat areas and they more than anyone understand the importance of security and the potential impact any OPSEC violations could have on themselves and their fellow Soldiers, Airmen and Marines."