Browsing the MSDN Architecture Center I ran into a nice article on descriptions and comparisons of the major Enterprise Architecture frameowrks

I always go back and forth with my feelings on Enterprise Architecture.  Everyone knows we need it, but it's so hard to get right that it has a pretty bad reputation in most large organizations.  Enterprise architects tend to be seen as "academics in the ivory tower" whose work does not have a major impact on day to day operations of IT. 

 As with everything else in IT, I think the forgotten aspect is people.  When done poorly, enterprise architecture design is a multi-year project that is done mainly in the "CIO's office" and does involve the IT team on the ground.  It ends up consisting of many documents (artifacts) that no one will ever read again once the project is completed.

 When done well (as described in parts of the article), it gets buy-in from the business at the start and involves the people who are currently developing and maintaing the IT infrastructure throughout the process.  The article talks about bringing in a consultant in most of the hypothetical scenarios, but this can be very hard to do right.  The consultant must be an expert in enterprise architecture but also has to work extremely well with others, since we all know how IT people tend to be when outside consultants are brought in to augment their work.

 Read the article, it's a good description of the different frameworks and might give you an idea for which (or which set) may work for your organization.