In today's world, businesses need to be flexible and agile so as to better respond to market changes. This requires IT that supports the business to also be flexible and agile and yet the vast majority of companies have complex processes that are often not documented and their IT assets, which they have invested in heavily, are rigid and silo oriented. To become flexible and agile from both a business and IT perspective without throwing out existing assets and processes is the challenge. SOA for IBM is all about ensuring that their customers are able to improve their business process and exploit their existing IT assets by componentising them into services.
The first thing that puts IBM on top of the analyst pile is that they understand both the IT and business issues faced by companies wanting to take this agile, flexible route.