Hi Sumit,
Ariba provides a suite of tools, processes and services for management of spending, including sourcing of new suppliers. How you make the best use of the tools and go about doing it is largely dependent on your specific goals and requirements. I'll give you a specific example of how this might play out for sourcing of facilities management, engineering or construction might work.
1) The Ariba Sourcing tool is used to conduct an RFP or RFI seeking new suppliers for a particular service. (Say facilities maintenace)
2) You have a list of potential suppliers, but you are open to finding new sources, so you use the Sourcing capabilities to connect to Ariba Discovery and find some potential suppliers to participate in your event.
3) After the conclusion of the Sourcing event, you choose an facilities supplier and use the Ariba Contract Management Tool to manage the specific contract terms and compliance to those terms.
4) After a few months you realize the incumbent supplier is not always available, so you set up a more adhoc type of sourcing event using Ariba Services Procurement to find a temporary replacement.
So to answer your question, yes you can use Ariba to source suppliers for any type of service. We have been doing this for years, but it really comes down to the specifics of what you are trying to accomplish.
Hope this helps,
Tommy Lee
Ariba Consullting