Phil Waineright recently posted on the use of virtual appliances as an enabler for SaaS to get inside the firewall:

“Delivering software as an appliance brings many of the same benefits as delivering software as a service. . . So, there’s a sense in which appliances are not so much a part of the SaaS model as competition for it.”

Rich Miller` commented further

“The bottom line is that SaaS has much to gain from embracing packaged software appliances, as both an infrastructure for on-demand service and as an on-site adjunct to their network-resident services.”

Folks are already using AppLogic to enable SaaS offerings without building the traditional multi-tenant application, so I read both posts with interest. I understand the desire to get “inside the firewall,” as Phil describes, but I’m concerned that he’s over simplifying when he says that vendors deploying virtual appliances on-premise “can push out a release to the entire network all in a single operation.” Major customers granting such ready access through their firewall for a vendor is outside my experience. We do, however, have users who’ve set up a virtual data center for a key customer as a secure operating environement.

If you’re operating a SaaS provider both posts are worth reading.