HP is dropping PA-RISC support in favor of Itanium, so it would be a good idea to bring HPUX to Proliant servers according to McNealy. The only people interested in this are the ones where HP is not interested in. HP is quite happy to have their top of the line servers running on proprietary processors. HPUX and the servers it runs on are an excellent excuse to charge immensely large amounts of money on hardware, software and services. The hardware is not at all that hot (although it very well made and still contains nice features, but nothing much has changed for years), the software is crap, most to blame is HPUX itself, but almost all HP implemented software has this over-complex-bloated-bug-ridden status upon it (compared to Solaris or Linux, which most of time still follow the KISS principle).
No really, if HP would want to go to the Proliant platform, they'd do better to drop HPUX and go Linux. No reason why they wouldn't be able to make great Linux specific servers with quality support. Ofcourse, that would make them just another Linux vendor, but now they are just another Unix vendor with an outdated product in their hands.