Should software firms block social networking sites ?

In recent past we see lot of activity in social networking using websites. The sites like orkut, hi5 , Yahoo 360, MySpace are few in this sphere. People check less of mails or post less of blogs, but they make it sure that they log in into one of these site and check for new friends or communicate with the old ones often.

1. But is this activity increasing to the level that it needs to be blocked so that the normal buisiness is not affected ?

My opinion would be no. Its managements responsibility that people are connected socially. And when you work a lot and you are mostly near your computer and connected to internet there is no better way that these networking sites.
I use lot of Orkut, it helps me manage my friends, find old/new friends, get to know about people, above all that make best use of extra time.
Hope there is a time when you can find every one in this world in networks like these, the world open and every one is reachable as in case of Orkut.