A small blurb on Sony's UK site has generated a lot of interest and speculation
Sony is expected to offer optional hard drives for the PS3 with potential memory capacity of 80 or 120 GB. It remains to be decided whether the standard version of the PS3 will come complete with a hard drive. The operating system has also yet to be clarified. The integrated Cell processor will be able to support a variety of operating systems (such as Linux or Apple's Tiger).
It's doubtful that there are any plans behind such statements. Sony appears to simply be positioning the Playstation 3 as a fully capable computer... capable of running any software... provided that it is offered by the developer.
An Inquirer article offers some similar comments from Sony's Ken Kutaragi:
Kutaragi said the PS3 will run operating systems as applications. "The kernel will be running on the Cell, and multiple OSes will be running on top of that as applications. Of course, the PS3 can run Linux. If Linux can run, so can Lindows. Other PC Operating Systems can run too, such as Windows and (Mac OS) Tiger, if the publishers want to do so. Maybe a new OS might come out," he adds.