While most IT decision-makers are still quite reluctant towards the implementation of enterprise-level cloud services, a growing number of firms is nevertheless currently investigating and running pilots to establish whether those would be suitable and economically viable solutions for their businesses. With this new market opening, it's inevitable for vendors to come rushing in, and Forrester sees both IT service providers and telcos gearing up to offer cloud services to enterprise clients. Unsurprisingly, potential savings are one of drivers behind this growth in interest and with shorter ROIs, these are particularly appealing to enterprises needing to upgrade in this climate. This emerging services technology is typically based on the concept of standardized, billing based on consumption, scalability, and access, but can vary considerably from one provider to another at this day. Web-based offerings, SaaS, PaaS and IaaS represent the typical general types of cloud services, but those are more-or-less covered depending on the current vendor capacity. On top of this, as with any emerging technology, the lack of maturity can be a hindrance. In this case, enterprise IT decision makers need to analyze vendor offerings in detail to make sure their provider has the necessary real latent capacity, that can easily be turned on or off, and that the offering is not merely a claimed utility or on-demand service capability, with the appeal of cloud services but lacking the core processes.

You can read more about this in Paul Roehrig’s series of documents "Cloud IT Services Market Overview — Real Enterprise Value Or Just Vapor?"