I think they just want to add more coupling between the two platforms. Sure enough, Twitter could write such a platform on their own but perhaps it's more time-

I think they just want to add more coupling between the two platforms. Sure enough, Twitter could write such a platform on their own but perhaps it's more time-efficient to just buy legacy technology and adapt it. Even more so when you get the staff who built the said technology along with it. Another aspect is the user-base that will come with Posterous.