EAI and SOA : Is your enterprise ready for it ?

That really depends on what you understand by SOA in the first place. In my experience the term SOA is used instead of 'application interface'.

The true difference is SOA returns an answer to a question, or performs a task when asked. In recent examples I have seen interfaces pass data between applications, the receiving application then decides what to do with it. A simple case is sending an invoice, the message could be in EDI format or whatever but this isn't SOA, it doesn't matter if the message travels across 1 or more middleware layers it still isn't SOA. A good example of SOA is tell me the price of a flight on x-airways for next tuesday. If the question is specific enough a response can be made.

To answer your question, I have not seen any applications that are advanced enough to take advantage of the SOA architecture. There are some technological hurdles that need to be removed first around language. Todays applications are analogous to human tribes all speaking different dialects. Without a translator we can not communicate, and translators are expensive and need to keep up with the evolution of languages used within each tribe. Tim Berners-Lee is doing a great job at tackling this problem (see Semantic Web). To keep the analogy going english as a common standard language advanced when dictionaries were created and easily distributed. To enable SOA and reduce the cost of integration the business community must invest into a common business dictionary (ebXML and Rossettanet are a good start) but these are not widely implemented simply because existing applications would need an expensive and significant change to embrace this technology.