I'll give you the highlights
1) There is a web interface for the standalone version, we intend on selling that as an *appliance* not as software. This includes a hardware acceleration component that pushes performance up orders of magnitude beyond what PG can do now. Price-wise it would be competitive against other anti-spam appliances
2) As a managed service, we've been running a cluster for the federal government for a few years now. This makes sense if the client can't/doesn't want to manage the equipment on site. Pricing for this is monthly, depending on the number of devices.
3) As a SaaS, where we process through our infrastructure. Like postini or mxlogic. Priced by the user.
We've sold all 3 for years and never talked much about it to be honest. Chalk it up to being an engineering company first and a marketing company a distant 10th
