I get quite a few questions, mostly from people I work with, about Oracle's own E-Business architecture. Fortunately, Oracle's Steven Chan responded to these questions in his own blog. Both this particular post and Steven's entire blog are worth checking out.
The article on Oracle's own E-Business architecture is at http://blogs.oracle.com/schan/2006/07/12#a429
You can find Steven Chan's Oracle E-Business Suite Technology blog at http://blogs.oracle.com/schan/