Will Sony release a PSP-4000?

Rumours seem to be flying around the web that a PSP-4000 is in the pipeline. The people on the web are saying that it will have a UMD drive like the 3000, 2000 and 1000, but unlike the PSP Go which has downloadable games from the Playstation Store via Media Go. You can download these games for the 3000 as well, which not many people seem to have done, but just informing you that downloads aren't exclusive for the Go.

I can't see a 4000 in the line, I don't know what Sony could add to it. Maybe a software update for the older models with facebook, twitter and so forth, but not in a new device. The 4000 might have just been the yearly update for the PSP, but Sony has missed the Christmas slot they have used for the past few years. Maybe it will be in time for the summer, but I see no point in that.

Whether Sony releases a PSP-4000 or not, it seems that rumours will spread around the web until it is dismissed or confirmed.