Depends on the issues your discussing. Isn't blogging about policies and issues effecting, or could potentially effect, good order and discipline the same as running to the press (in uniform) and expressing your opinion, anonymous or not? Questioning leadership should be off limits by those in service in such an open forum such as a blog. Discussing future platforms, leadership pointers, port visits - a "day in the life" sorta stuff is where I see the active duty blogger.
I say "in uniform" when the blog, where anonymous in name but not in service connection, touts a certain affiliation.