SaaS - really? or just a website!

I've blogged before about the way that tech acronyms have been used in marketing so that their real meaning gets diluted.
One that is currently being diluted by the tech world itself is the term Software as a Service (SaaS). It seems to be used for almost anything that is online and has a subscription model! I think that misses the definition of Service. I would argue that you are only really offering a SaaS if your software's web interface is only 1 of several mechanism's by which your "service" is delivered. This almost always means that you have an API, and truely it should be open and comprehensive with your own product built on top of it - i.e. no backdoors to data! A SaaS product will be looking for opportunities to integrate with other solutions, to share information. Software delivered via a website will be closed, difficult to share information with, uninterested in partners despite using the term service and having a monthly a subscription fee.
	Part of the differentiation between SaaS and Software as a Website (SaaW) is that a company who truely sees the benefit of an open, collaborative platform will want to attract partners. Being open allows other people to build the bits you don't have time for, or even know would be useful! To do this well you need more than an open API. This simply satisfies the PULL aspect to your data... what about the PUSH? (Please tell me you didn't plan on people polling your api for changes in data).
	I promote thinking about an event based model to your architecture that will allow you to attach subscribers to changes in your underlying data. This will allow you to PUSH information to those people who want to know about it. Just as defining a well thought out API is difficult, so is defining how to expose events that can be subscribed to. More on that subject in another blog post.