There is probably the best discussion about Architectural photography that I have participated in for along time going on right now on the Luminous Landscape forum. Comments and suggestions by some top APs from around the world. This doesn't happen often.
Becoming a great Architectural Photographer!?, Suggestions for becoming a great Architectural Photographer.
Part 2: "Becoming A Great Arch. Photographer, Now you've decided to pursue Arch. Photography - what to do?
Becoming a great Architectural Photographer!? PART 3, Business Practices, Marketing, Billing, Networking, etc.
and some AP photography related threads:
Canon 24TS-E lenses compared with rodenstock 35HR, tested on the canon 5dmk2 and the sinar emotion 75lv. Some good comparisons of AP cameras and lenses-MF vs. DSLR
Canon 17 T/S compared with 23HR
Read, enjoy and participate!