Underestimate the complexity of implementing Web Services, SOA, or EAI and you will likely pay a steep price. Vendors and some industry analysts like to tout this as the easy part. Just use standards and this stuff is pretty easy. All you need is the 850 standards and their toolset.
I'm sure the getTemperature("Insert your zip code here")they tried once was pretty easy. In reality Integration work is pretty complex. There are a lot of contributing factors to the complexity that no one really addresses when hyping it up. Some of these factors include: Complex Business Rules, Data Enrichment, Infrastructure dependencies, Interoperability, Standards Interpretation, Distributed or Silo oriented Development teams.
Integration Architects have their hands full trying to make all of this stuff work. When you consider that some of the biggest reasons for adopting EAI, Web Services, and SOA is reuse and agility, these are in fact some of the hardest benefits to obtain. My advice from hard earned experience, do your homework before you go down these paths. Nobody wants to explain to their business units why its not possible to reuse any of the services you just deployed for several quadrillion dollars. Not to mention they aren't reliable and they don't interoperate with any of your other technologies or platforms.
The bright side is that is possible to achieve these benefits. But did I mention the homework part? Oh and when the vendor says it's easy, Run Away!