Sun has just cut a deal with VMware that results in the hardware company increasingly donning the clothes of its competition. The official line is that "Sun is offering the VMware infrastructure product suite on Sun hardware systems with full support from Sun."

But why would the company do such a thing - and what does it mean for its customers?

According to corporate development manager Ben Lenail, the deal means that Sun achieves parity with mainstream server vendors such as HP and Dell. It means, says Lenail, that Sun will become "a fully-fledged VMware OEM" by bundling all the company's infrastructure products. All, that is, apart from VMware's embedded hypervisor which Lenail said was too new to consider. "It's not clear what market share it's getting," he says.

If you're selling stuff, then you need to support it, and Sun reckons it's got this covered. "We'll be providing frontline support for VMware on all Sun product workstation, server and storage products," says Lenail.

So the next question a potential customer would ask is why on earth Sun, which already has its own, fully developed set of virtualisation technologies, would want to resell those of the clear market leader. The rationale for the move was "pragmatic," said Lenail. "We see customer demand for ESX and associated products, and we need to be competitive in terms of products and support. We want to be the volume leader in the x64 space."

It's clear that Sun isn't going downmarket. "Sun has no plans to go into 32-bit computing," said director of Sun's xVM system management division, Vijay Sarathy. "We're not ever going to be a Dell or go into the mid-market. We have to pick our fights and we're about mission-critical enterprise computing, such as databases."

"But on the management side, we are working with VMware to ensure that VMware VirtualCenter integrates with Sun management products," says Sarathy. "We have systems and point products now, but what we've been doing over the last year is rewriting these products under the Sun xVM OpsCentre brand.

"It's designed to be a single console management to your physical infrastructure today. We'll add virtual management in future but today you can plug in servers and we will discover, identify and provision them with firmware and operating systems. Then you can patch and manage them, whether they are Sun or non-Sun systems."

Lenail dismissed the issue of VMware competing with Sun's home-grown virtualisation technology. "We want to offer choice - we support everything. This is the culmination of our relationship with VMware."

"We're really trying to be heterogeneous and trying to address the wider market," reckons Sarathy. "Windows is the dominant server OS with 70 percent market share. And we're open - remember we have an agreement with AMD to develop Solaris for Opteron - and we already work with competitors including Microsoft."

But behind those words lurks a hidden truth. While Sun's financial outlook appears to be improving - after a dozen or more quarters where the company was leaking cash - it's also being boxed in. Sun likes to present itself as a software company - it hardly wants to repeat the same errors that Apple made - but in truth it's a server company. And its server market share is not improving, as Sun's heartland Solaris/Sparc workloads are migrating onto x86/Wintel platforms - and even back onto the mainframe, if IBM is to be believed.

On the software front, Solaris is being overtaken by Linux and Windows and its Xen-based xVM virtualisation platform doesn't appear to have dented VMware much - despite financial analysts' disappointment over VMware's recently-reported quarterly growth slowdown to a mere 88 percent. They should complain.

And with an update of xVM due out in June which Lenail reckons will result in much higher I/O performance, it's hard not to see this VMware deal as a bit of a Trojan horse, set up for the publicity and general good vibes it would garner; the announcement was made in the middle of VMware's industry event VMworld. And who knows, Sun might even sell some VMware product, which is better than not selling any.

The agreement does provide Sun with a fig leaf between now and the new release of xVM, and of course it's no bad thing to be associated with and be a reseller of products in high demand, such as VMware's. But it's hard to imagine many customers outside of Sun shops taking the move too seriously.