What's the problem with a ceasefire?

For obvious reasons, I very desperately want a ceasefire in Lebanon, so I won't do any special pleading, but here's a question: What would be the problem with a ceasefire now?

More directly, what will a nation that defeated the entire Arab world in six days accomplish next week that it hasn't accomplished this week?

OK, one piece of special pleading by comparison: Speaking strictly as an American, if the insurgents in Iraq offered a ceasefire, I'd take it in a heartbeat.