That's not necessarily a bad thing, either; one of the biggest advantages of cloud or SAAS is that they take some of the load off IT. If it puts your whole department out of a job that's not a good thing.
If it just shortens up your project backlog, so much the better.
Letting them do that with no management or coordination will not only waste money, it will spread your corporate data across half a dozen SAAS or cloud providers. That makes security and compliance almost impossible because you have no direct control over most of it and no idea which version is accurate – let alone demonstrating you're complying with reporting regulations or even knowing what much of the company is up to.
Pick the right cloud
Even the biggest advantage of a cloud app – that it's housed in someone else's data center and can expand or contract to meet the customer's changing capacity requirements – isn't set in stone.
A private cloud means you can distribute your compute resources more efficiently across all your data centers, applications and departments, but it's not as flexible as using someone else's data center. You still have to buy new servers if a seasonal spike tops out everything you have on hand.
Public clouds are better, but there's a tradeoff there, too. If you don't mind running your applications on virtual servers that run on the same physical servers as VMs running another company's software, you can add or subtract resources on the fly and up to physical limits on capacity that are far beyond what you probably have in your own data center.
Isolation and security
If you want a little more privacy – or are required to want it as many federal agencies are – you can't share physical servers with anyone else.
A lot of non-government agencies do the same thing just because they're uncomfortable running on the same boxes as companies that might be competitors or that might have far too much interest in seeing if there are little holes in the VM infrastructure through which interesting data can leak.
Providers often describe that arrangement as a "private cloud," but you have to make sure about the specifics.
All the apps run on VMs, so they're taking data in through network ports they share on the physical servers on which they live. Do they also have to share the networks that link those physical servers to the Internet and eventually your data center?