Tom Yager at InfoWorld - Apple Xserve: The final review:

"While trends, or rather, the analysts who proclaim them, are pointing to the triumph of software as a service, outsourced applications, consulting, node-locked operating systems and other pay-as-you-go approaches, Apple is piloting a rocket-powered sled in the opposite direction.

Apple is going to sell complete server platforms that buyers purchase, operate themselves and actually own. Seriously. [...] There are no subscriptions, no priority update service fees, and no client, device, mailbox or CPU licenses."