A few months ago, we heard that HP was tinkering with the idea of selling machines stock with Linux. Details were light, but after the warm response Dell received for their introduction of desktop-class Linux machines, it seemed plausible for HP to consider it as well.
It looks like that is now becoming a reality. HP will expand a test program across several countries, greatly increasing their existing Linux portfolio. Where it might really get a chance to take off, however, is in the educational sector especially in the U.S. This would ultimately results in them moving away from Linux solely as a server solution, and begin pitching it as a desktop solution.
If their pilot goes well, I imagine we'll see them offering desktops with Linux just the same as Dell is doing now. The article mentions drawbacks to doing it exactly like Dell did, which might make you wonder what distro they would choose to back.