There has been a bit of talk here and there about the possibility of a PSP branded phone. Thus far there hasnt been a whole lot of official word coming from Sony on the subject, however, Marketing Week has a little bit of insight on the subject
They have sources that have led them to believe that the relationship between Sony and Ericsson has become a bit strained. They have also learned their lesson with handing over the Walkman brand name to Ericsson so its doubtful they will let them get their hands on the PSP name.
They believe that the phone could be released in time for Christmas of 2009. Analysts have said that it should be fairly easy to convert the PSP into a phone, since it already has Wi-Fi.