John,
Bring your serious gear -- well, some of it anyway -- for that object lesson (and maybe a little demo also).
And what kind of architectural photography would you discuss? Would there be talk about natural lit, indoors stuff? In that case, you *might* want to talk about the WB issue even when using digital RAW. For the utmost in quality, one really should *not* merely rely on digital RAW for color-correction/setting in post, but should probably use good color filters (or use more neutral lighting). Digital color-correction in post (away from the camera sensor's native color bias/balance) will necessarily lose quality same as w/ film. There is no free lunch.
But yeah, I imagine you'll need to whip out them tilt/shift lenses for your digital body too.
Personally, I don't know what else I'd expect other than discussion on compositional techniques (that lend themselves more to this type of photography than others), lighting techniques (and/or use and choice of natural light), and such things. And of course, you'll probably want to point out what gear suits what approaches/styles/etc best for whatever given situation.
I don't personally know, but I imagine you might also want to mention stuff like the use of a light meter (vs the camera's built-in metering), if time permits.
And in the end, a practical demonstration w/ some actual shooting along w/ providing some hands-on exercises for the club members would probably be good, if time (and location) permits. There's nothing like actually getting into the act of doing it in order to get a better grasp of the how's and why's of it all -- and making it fun for all involved would probably be great too.
Have a blast w/ your talk!
_Man_