Phil McKinney, CTO of HP's personal systems group, gave an interview for The Seattle Times, and shed some light on this issue.
First of all, this is not a virtualization mode (and HP is not dumping Windows altogether), but rather a webOS integration - one, which will target to bring an ecosystem consisting of phones, slates and PCs - and one that's good for both the business and the casual user. It seems the main word here is differentiation - a way to stand aside from the rest, not unlike Apple did some time ago:
"Q: So HP's taking Apple's approach, with integrated software and hardware development?
A: I think the key is that if you want to differentiate in the marketplace you need to be able to control the key points of the differentiation."
We don't know about you, but we can't wait to taste the webOS integration on our PCs.
source: Seattle Times via PreCentral