Nice article! I've been playing with the Xen Demo CD, which was quite nice and booted up mulitple OS'es at once (VERY EASILY)! Xen is really the future I suppose... especially with VT and Pacifica.
If you want a server based on Xen, a hosted solution:
There are some XEN VPS providers (http://www.budgetdedicated.com/) (BudgetDedicated, and Bytemark also very soon) that offer Xen as a hosted solution. They have an excellent datacenter location in Europe and good performing hardware. I think I will never go back to a dedicated host again, because it's more expensive and actually has less performance (because VPS providers can buy better hardware because they collect the dedicated hosting revenue multiple times).
Really worth it! 7 Day Trial accouns are even for free at BudgetDedicated (http://www.budgetdedicated.com/) .