Why Service-Oriented Architecture?

We are focusing on SOA from an architect’s perspective. Questions an architect usually will ask regarding SOA:

What is the driving forces for SOA
Why should I consider an SOA approach
How do I get started implementing SOA strategies in my application development
Do I need new tools and servers
- If so what particular solution types should I consider
If so who are the market leaders
What are the big benefits for SOA such as integration
How can I judge if SOA would provide a return on my investment
What are the market forces driving this and who are the market leaders
If I am considering SOA what are the things I need to watch out for