SINGAPORE, Sept.

Twitter co-founder Jack Dorsey announced Monday that he would be returning to the popular microblogging service as the company’s executive chairman and would be heading up its product development team.

As Twitter closes in on its fifth anniversary, the microblogging site boasts a billion tweets a week with over 200 million registered accounts.

NEW YORK, Feb. 10, 2011 /PRNewswire/ -- Vivienne Tam announces the launch of a limited edition "Double Happiness" Square credit card reader. Square is a revolutionary service enabling anyone to accept credit cards by plugging a card reader into your phone or iPad.

Twitter’s co-founder, Evan Williams, announced Monday that he would be bowing out as CEO of the micro-blogging network so he could focus his attention on other areas of the company where he feels he could offer more support.