SOA, or Service Oriented Architecture comes up in discussion a lot these days. More and more, as VoIP evolves toward true unified communications, SOA plays an important role. Here's a link to a nice, simple writeup on SOA

SOA in Plain Language
August 31, 2006
By James Maguire

Service-Oriented Architecture is set to create a revolution in enterprise applications, forever changing the software and service industries. But what exactly is SOA?

Service-Oriented Architecture (SOA) is big business – and it’s getting even bigger. Heavyweight vendors like IBM and Accenture are promoting it intensely. Forward-looking enterprises are moving to adopt SOA into their business plans.

In the view of SOA’s proponents, Service-Oriented Architecture has the potential to create a revolution in IT departments. It will blur the line between software and service, radically changing the software industry. It will save companies money, greatly increase productivity, and empower network architects to envision brillant new services.

The only thing it can’t do, apparently, is cook an egg in under two minutes. And with time SOA might even develop that capacity.

But amid the growing interest in SOA – and the grand claims about it – plenty of businesses are still wondering: should we get on board? And what exactly is SOA?