How have I overlooked this thread.
Haven't caught up on all the comments but my two cents.
With the increase in off road touring do long distance mountain bike trails like the great divide (2700 miles from Banff to Mexico) there has been a tremendous growth in the interest in ultralight touring
This growth is simply practical. Traditional panniers and racks don't fair well on rought trails. They perform poorly, catch on stuff and make it generally hard to handle the bike.
There's another awesome thing that happens when you go ultralight, new doors and possibilities open up. Most specifically multi-sport adventure. For example by combining a pack raft and a bike, or skiis and a bike one can travel across nearly inaccessible terrain.
i.e.
http://lostcoastbike.blogspot.com/
What's more this is starting to carry over into road.
http://www.flickr.com/groups/ultralightbiking/
So yes, ultralight touring is quite the thing for off-road, is it as important or effective for on road touring no. But I don't care about that so much as I'm just having crazy fun doing it.
UL road touring rig by
mmeiser2, on Flickr
Will respond more when I get a chance to read through the whole thread.