Hi Cyafa
The incident happened on the evening I arrived in Beirut for a short holiday (Tuesday Aug 24th). It was a little worrying to see on the news that there was the first trouble in Beirut for two years, but in practice caused me only one minor problem. One of the things I did was the excellent and highly recommended "Walk Beirut" walking tour (www.bebeirut.org) and the last 5 stops on this were cancelled as they were close to the area where the incident happened and there was "a lot of security" in the area. Having said Ronnie the tour leader fully expected to be including them again on last Saturday's tour.
I had a great time in Beirut and I'm sure you will too. Its worth keeping an eye on the local news as instability can always develop in Lebanon. You'll see quite a lot of security and a few tanks on street corners, but in general its a very safe destination and I found it really interesting and enjoyable
Nick