Can political journalists be partisan?

Mark Glazer makes an interesting point over at Media Shift

He quotes James Poniewozik who,writing in Time magazine says

In today's confessional era, reporters disclose private matters ranging from marriage to stock ownership. Everything except voting.

and continues

The reasons not to say whom you're voting for boil down mainly to the interests of journalists, not those of readers and viewers. It would be a pain in the neck. Campaign sources would mistrust you. Radio hosts and bloggers would have a field day. Readers would become suspicious.

But how difficult is it now to ascertain a journalists political laening in the age of the blog.Here journalists views will become clear,either intentionally or otherwise,simply in the subjects that they write about.