A panel of venture capitalists sounded cautiously optimistic about about the future of “enterprise 2.0″ this morning at the Office 2.0 conference in San Francisco. Some of the big themes were pretty familiar (hey, did you hear that the online subscription business model, a.k.a. software-as-a-service, still needs time to mature?), but it’s important to understand how these guys see the market — and what companies they’re willing to spend money on.

The biggest point of contention was how fast the market for “office 2.0″ (the new wave of web-based software for business users) will take off. Mayfield’s Robin Vasan was probably the most skeptical — the venture community “always overestimates” how quickly these technologies will be adopted, he said.

On the other hand, Dan Avida of Opus Capital said adoption is going to be a lot faster this time around because many people are starting to use this kind of web-based software at home home. Or, as Jeff Clavier of SoftTech VC put it, when someone tries out user-friendly office software for personal use, they want to “shoot themselves” if they have to use “Oracle-level” products when they come to work. Another good example: The comparison between Gmail’s ease-of-use, particularly ease-of-search, and Outlook’s.

Of course, Gmail’s recent outage illustrates why some of the bigger companies aren’t willing to trust software based entirely in the Internet cloud.

“If Gmail’s down for six hours, you can lose your job over that,” Clavier said.

VentureBeat’s MG Siegler has argued that the Gfail’s significance can be exaggerated — it’s hard to think of any tech service that hasn’t had problems — but it’s also a question of perception. Some companies don’t trust the cloud, and a single outage can confirm those fears.

When it comes to adoption, Clavier said an “office 2.0″ startup stands a better chance if its product doesn’t require any support from the corporate IT team. That’s one of the secrets to Salesforce.com’s success, he said — employees could just start using it on their own. A company that needs to integrate with SAP or a corporate database, on other hand, faces an uphill battle.

“If you need to go to Corporate IT, they’ve got 200 people ahead of you in the queue,” he said.

Clavier also offered more general investment guidelines — he looks for startups that target large existing marketswith established players who may have gotten big and sluggish, where “there is a habit from the enteprise to buy from these guys, but it’s not that they love these products.”