Half or more of the computing appliance vendors I’ve looked into follow very similar hardware strategies: They use mainly standard parts; they include uncommon but off-the-shelf networking (and sometimes encryption) accelerators; and they of course optimize the mix of those parts and general hardware architecture as well. (EDIT: I actually gave names to three strategies — even if they were just “Type 0″, “Type 1″, and “Type 2″ — in this overview of data warehouse appliance vendors. And in another post I considered arguments about whether one would want a data warehouse appliance at all.) Examples I’ve posted about recently include – and I quote the forthcoming column – “DATallegro and Teradata (data warehousing), Cast Iron Systems (data integration), Barracuda Networks (security/antispam), Blue Coat Systems (networking), and Juniper (security and networking).” (ANOTHER EDIT: But I think DATAllegro’s strategy has changed.)

By way of contrast, there’s also a group whose stance is more along “hardware/schmardware” lines. Sendio and Proofpoint (in most cases) don’t really do anything special at all in their boxes; what’s more, Proofpoint actually has significant software-only deployments over VMware’s virtualization layer. Kognitio and Greenplum think their software-only data warehouse offerings are appliance-equivalents too; indeed, Greenplum’s software is sold mainly bundled with Sun hardware (to the extent it’s sold at all), and Kognitio is hinting at an appliance-like offering for competitive reasons as well. Check Point Software plays both sides of the field; it offers its own kind of “virtual appliance,” but also gets many of its sales through appliance vendors. Its most interesting such partner, if not its biggest, is Crossbeam Systems, which in my opinion may very well represent the future of appliance technology.

• Demo (of course).
• Tweak, test, deploy – between patches and new anti-spam rulesets, Proofpoint users seem to have a rapid change/test/deploy cycle. Virtualization makes it possible to do that without having multiple copies of an appliance.
• Disaster recovery – this seems to be a big one.
• “Surges” – depending on what the bad guys are doing, one’s need for anti-spam servers can go up and down in a hurry. Virtualization makes it easy to respond.

It probably is not coincidental that Proofpoint makes less use of custom hardware that many other appliance vendors. In most cases, Proofpoint just buys servers from a vendor such as Dell and fiddles with their packaging. For some applications it does add enhanced networking capabilities, as other appliance vendors do; while I neglected to ask explicitly, I got the impression these weren’t the ones commonly deployed on VMware.

Proofpoint said that very few of its customers bought VMware in connection with their Proofpoint deployments; except in a couple of cases, they already had it and were using it for other things.