That's what the spy reports say, but nothing's official so far. These pics just showed up last night, but the rumors of a "prosthetic Tarkin" have been circulating for a few weeks now. I think they're done by the same FX crew that handled the makeup on Farscape, as I recall hearing a report that they had been contracted for some Ep III work.
Still, I'd take this with a grain of salt for the time being, at least until photoshop-savvy types can inspect them. The "other" SW sites are united in debunking them, but I think that has more to do with petty internet fanboy rivalries (PIFR, for short) than any actual analysis of the photos.