http://www.infoworld.com/article/07/08/23/Google-Apps-no-replacement-for-MS-Office_1.html

I have had an increasing number of conversations with enterprise customers and partners who are looking at consuming various components of their IT estate as a service. As an overall strategy this makes sense, as long as caution and an understanding of deliverables, SLA's and expectations is clear. Don't get me wrong I am a firm believer in the shift that is occurring in the IT industry. However one mustn't be naive to the impact such a large strategy shift has on IT and business.

A lot of these requests are being driven by smaller teams within organisation who start using some free web tools which then drives IT to consider adopting some of these services. If you like it's the consumerisation of IT.

Whatever your opinion on this topic this is a good background article and report.