At OpenStack Summit you'll hear plenty of arguments for how OpenStack has finally arrived as a business technology. And while there's cause to believe OpenStack is starting to make a showing that's as prominent (and permanent) as virtualization or Linux, there is equally good reason to remain skeptical -- and aware of how far OpenStack still needs to go.

Adrian Ionel, CEO of OpenStack vendor Mirantis, sees signs of significant OpenStack uptake. Not only is adoption of OpenStack spiking, it's acquiring conventional brick-and-mortal companies like Home Depot and John Deere as customers, which Ionel says reflects its arrival as a proper enterprise business technology and not simply an experiment.

Ionel estimates that Mirantis is adding 10 to 15 new customers a day -- people who download the product, try it out, and then later on hook up for a full support contract. Those customers include Alcatel-Lucent and Kaiser Permanente, he said.

"The folks who adopted OpenStack earliest were the webscale guys, the PayPals and the eBays,"Ionel said. "They had the level of technical expertise such that they could adopt something new and make it work if it made business sense."

But new OpenStack customers are far more mainstream, Ionel says, and existing customers are expanding their commitment as well. Expedia, an existing user, had one data center running OpenStack; it is now expanding to five.

Ionel says mainstream companies have started coming on board not just because OpenStack allows for faster internal development, but because of the speed of OpenStack's own development. They see the agility available to companies like eBay, and decide they want a piece of that as well.

Radhesh Balakrishnan, Red Hat's general manager for virtualization and OpenStack, said OpenStack adoption has two key uptake models: one where the core OpenStack offering is most valuable and the second where the partners and add-ons are most useful. The first mode is seen in telecommunications (a space Canonical is also laying claim to), where the players are reinventing themselves as service providers in response to market pressures and the need to shuck off legacy proprietary infrastructures. The second is seen in financial, public-sector, and research-oriented companies -- and also in enterprises -- where OpenStack is being integrated with existing storage, networks, or virtualization layers so the new and existing infrastructures can be managed together.

Nebula, which makes an appliance that automatically builds and maintains a cluster of OpenStack servers connected to it, strikes a more conservative note when describing OpenStack's uptake. Nebula has seen the biggest adoption for OpenStack in five verticals: government, higher education, genomics or life sciences, media, and now financial services.

Nebula CEO Gordon Stitt says the main issue isn't who's adopting OpenStack or at what pace, but in what form and to what end. Enterprises are rightfully wary of moving anything mission critical, and there are a number of steps involved in interconnecting OpenStack with existing legacy structures like storage and identity. "Enterprises may run their websites on OpenStack," Stitt pointed out, "but not their ERP."

Rather, Stitt believes enterprises may find it more appealing to erect OpenStack structures in parallel with existing infrastructure and build business value with it that way. "You're not necessarily going to move your stuff to a new OpenStack cloud right away," he said, "but you may run analytics on the data in it with OpenStack by reaching into it and performing new functions on it."

Media, content creation, and life sciences struck Stitt as good examples for where OpenStack enjoys stronger greenfield adoption. Those areas revolve around the generation of entirely new data, rather than the manipulation of existing data; everything newly created can simply be deployed fresh into OpenStack.

It's hard to ignore the overall enthusiasm around OpenStack -- the near-doubling of attendance to 4,500 at this year's summit is a sign of how interest is mushrooming. And the overarching presence of Red Hat shows how it's working to make itself as synonymous with OpenStack as it did with Linux -- but the existence of other vendors all vying for attention also raises a cautionary note that, open source notwithstanding, the OpenStack market runs the risk of becoming as fragmented and contentious as Linux itself.

[An earlier version of this article noted that HP and IBM did not have booths on the OpenStack Summit floor. Both companies have both booths and panelists.]

This story, "Don't celebrate OpenStack's success just yet," was originally published at InfoWorld.com. Get the first word on what the important tech news really means with the InfoWorld Tech Watch blog. For the latest developments in business technology news, follow InfoWorld.com on Twitter.