The use of IBL for architectural visualization is mostly related with external views, and furniture design, where we can add the model into a scene that looks like a studio setup to generate reflections. I still remember the days where we had to use external render engines to use HDRI in Blender, and most artists couldn`t rely on this type of lighting. With Blender 2.5 things get a lot easier, and we can use IBL with Blender internal render.
If you never used IBL on a project, here is a great opportunity to learn about IBL. An artist called LaH, posted a tutorial about how to setup IBL using three different images for lighting.
This could help a lot on external visualization projects for architecture.
