Allen has quietly become more active on the microblogging site in recent days, having posted several updates to his account, including a post on September 22 that he was in Hawaii working on a book and more recent updates talking about his NFL team--the Seattle Seahawks--and a brain research summit he recently attended.
David Postman, a spokesman for Allen, said the @paulgallen account has been registered for a while, but was formerly private and not really being updated.
But, Allen has been reading a lot on Twitter lately, including posts from Gates and from Seahawks coach Pete Carroll.
"Pete Carroll tweets a lot," Postman said. "Paul has been following him. I know he follows Bill too."
With Allen feeling better after a second bout with cancer and starting to travel again, Postman said Twitter offers a good way to connect with the public.
"It's a way for him to share what he is doing," Postman said. Allen has, for the most part, avoided the limelight, although he recently made some headlines when he joined Bill Gates' giving pledge and agreed to donate the bulk of his wealth to charitable causes.