All indications are that Israeli artillery shelling has really stepped up at the border in the past few hours, possibly setting the stage for a ground invasion of South Lebanon. The recent attack on Haifa might have sped up the timetable.
i think the tipping points are going to be what does Hizbullah do at the point of invasion. The use it or lose it mentality may kick in and TelAviv might get hit provoking an even stronger IDF response. The other point of no return, particularly with regards to syria, is whether the IDF ventures into the Bekka which Assad would have a tough time dealing with politically if he doesn't put forward at least some type of token reponse, which might not even be necessary b/c the IDF may take proactive measure to protect their flank like i mentioned in my earlier post