According to GameInformer this is actually true. Sony Worldwide Studios President Shuhei Yoshida confirmed this rumor in the latest issue:
We also felt — like many users — that we wish we had a second analog on the PSP. But we are talking about the mid-life cycle of this platform, and the PSPgo is designed to be perfectly compatible with the PSP-3000 and all the games that released before that. So we had a very serious discussion about this particular subject, but we decided not to add a second analog, and some of the developers are doing quite a nice job translating the second analog functionality to different buttons. We didn’t want to divert their efforts either.