I have spoken with many enterprise architects who have a plethora of applications in their enterprise and are trying to integrate them to fulfill the enterprise's strategic business directions. There are two patterns I see to fulfill this need.
The first, and most common, is "integration at the glass". This is, writing a mid tier application to pull together disparate applications into one view for the user. These applications may also share data with each other via this mid tier application. Some people may refer to this as a "portal", which it is - being built in house or purchased. In the long run, integration like this may get you into trouble due to tightly coupled point to point integration.
The second pattern I see is a more strategic direction around a full SOA type solution with integration via an ESB. This architecture provides a robust enterprise integration at a business layer while still leaving room for a nicely placed view of the enterprise via a portal. In this case, it's not so much the portal doing the heavy lifting, but more about putting the functional pieces together.
Enterprises tend to build one or the other to meet business objectives - and may have many across different LOBs. In an ongoing blog, I plan to write about what I have seen that leads to these patterns being put in place and how enterprises can better position themselves in the long run for a better strategic architecture.
I also have experience in many other areas of the enterprise - so their definitely will be tangents along the way!
More to come....