"Incremental" is perhaps the most important word in the SOA vocabulary. In a recent post, Jack Vaughan reminds us of the case for incremental SOA, backed up by observations from Randy Hefner, Mike Rosen, and the Rolta excellence center.
Rolta advises "two-to four-week sprints" for SOA-based projects, and Rosen advocates "understand your requirements, look for a small incremental approach at addressing those requirements, get continuous feedback from your sponsors and look for some way to prove the value."
Always good advice. Remember, inch by inch, it's a cinch. Mile by mile, it's a trial.