The legislature is not in session, so it's not like there were going to be bills piling up on his desk awaiting signature or veto.
Emergency? South Carolina's constitution provides for that:
In the case of the temporary disability of the Governor and in the event of the temporary absence of the Governor from the State, the Lieutenant Governor shall have full authority to act in an emergency.
The Democrats are trying to make hay, of course:
"Being a chief executive means being on call all the time, and Gov. Sanford either doesn't get that part of the job or can't handle it," Hari Sevugan, a spokesman for the Democratic National Committee, scolded.
I rather suspect that Sanford was, in fact, "on call" in case of emergency ... but the tabloids and the Democrats getting their panties all in a wad over his whereabouts doesn't constitute an emergency (as a matter of fact, file it under "business as usual"). Just because Mark Sanford's staff wasn't telling Hari Sevugan (or anyone else) where Sanford was, that doesn't mean Mark Sanford's staff didn't know where Sanford was.
Get a grip, folks. When you take a vacation, do you leave messages on Mark Sanford's machine so that he can know exactly where you are at all times? If you don't, why should he?
Update: So it turned out to be about who's shtupping who in the non-political sense of the word. No, I'm not surprised. Yes, I'm still all so-whatsy and who-caresy. Maybe even more so -- above and beyond the fact that all these yahoos had no "need to know" where he was anyway, "I'm going to Argentina to shack up with my forbidden lover for a week" is precisely the kind of thing I'd keep to myself too.