Check out Digital Forest. I'm not crazy about their shared hosting, but their colocation is tops, and they have a ton of experience with xserves, to the extent of sending some design advice Apple's way:
http://chuck.goolsbee.org/archives/126
DF isn't the cheapest, but their pricing's reasonable, and they're highly reliable. TidBITS has used them for years, among other Mac luminaries.
by Nat — May 17
http://chuck.goolsbee.org/archives/126
DF isn't the cheapest, but their pricing's reasonable, and they're highly reliable. TidBITS has used them for years, among other Mac luminaries.