It would appear that the Pakistan Cricket Board has made the most obvious move rather late. However, they believe they are taking one more step towards ensuring the Pakistan cricketers focus only on, well, cricket.

The Pakistan Cricket Board have been clearly rattled since the wicket keeper, Zulqarnain Haider, fled from the Pakistan team hotel in Dubai to land in London. While the Pakistan team officials were frantically trying to discern his whereabouts, the one place they did not look was at his social networking pages.
Haider had stated, for the entire world to know, that he was being hounded by bookmakers who were allegedly pressurizing him to fix the fifth ODI of the Pakistan South Africa series and angry with him for having help Pakistan win the fourth ODI.
The sudden take off by Haider and his disclosures upon landing in London have greatly upset the Pakistan management who felt Haider should have shown more faith in confiding to the team officials or the PCB rather than portray PCB in a poor light, particularly after the scandalous Pakistan tour of England that included allegations of spot fixing and match fixing, for which Salman Butt, Mohammad Aamer and Mohammad Asif are awaiting the ICC hearing.
To prevent more Pakistan cricketers becoming broadcasters in their own right, the PCB has stated that clauses would be incorporated into the Pakistan's centrally contracted cricketers who are now banned from using social networking sites such as Twitter and Facebook.
There has been an ambiguous, unwritten rule amongst teams about what they can and cannot post on the sites. The recent case of Kevin Pietersen and Dmitri Mascarenhas as also the young England captain who went all out on his Twitter page, it is clear even the ECB has had to tow a fine line from banning cricketers altogether from using the sites.
There has also been a great deal of problems with fake profiles coming up in the name of the cricketers, leading fans to believe they are the real thing. While some cricketers have chosen to use the networking to reach out to their fans, with some using it to even announce the progression of their dalliance - Shane Warne and Liz Hurley would be the prime example - others have chosen to stay away from the social bug altogether. The PCB is now clearly dictating the latter as Pakistan embark on the tour of New Zealand.
Twitter troubles have not escaped other teams either wherein the BCCI had a little trouble with the likes of Yuvraj Singh and Rohit Sharma while Sachin Tendulkar on the site became a charitable campaign for cancer. Even the South African captain, Graeme Smith, chose to dig into the then selector, Kepler Wessels, for comments made about the team's performance.