'Software as a Service' has been around for years, but is now (September 2008) being pushed by many of the publishers as the next big thing.

Basically, rather than installing any software, your client machines connect over the internet to receive the remote service.

Licensing?
Licensing for SaaS is usually user specific, the idea being that each user can then log in from any device.

SAM?
Managing SaaS is incredibly easy from a compliance perspective because if a licence isn't in place you won't be able to access it.

From a cost perspective much of the same issues arise as with locally installed software.  You still need to manage your user account numbers otherwise you could be paying for users that no longer use the service.

Examples of SaaS
Google docs is a great example of SaaS where all you do is create an account, pay the fee (if there is one) and off you go.

Points to note with SaaS
Some SaaS models are not quite so simple, where the provider is less clear around the licensing.

Make sure when you are entering any kind of service provided contract that licensing is clearly discussed in terms of responsibility and who pays what and when.

Licensing should also be very simple to manage, just like the Google service.  If it isn't then work with the provider until it is.

We now look at Virtual machines...