Devan,
Hey hey.
I was thinking about this the other day.
With the Multi-Server example, my theory (haven't actually coded anything yet) is that you would start off by checking in the webhandler of the server that redirects, and based on what got parsed out of p_web._UserAgent (not .UserAgent, doesn't have enough info) I'd redirect to the needed webserver.
This is a scenario where you have separate web servers for each "type" of device (mobile, tablet, computer).
Don't know if it's feasible, wise or even possible.
It would probably be easier, now that I think about your question a bit more, to just examine p_web._UserAgent in the WebHandler of the webserver solo (only having one, not multi-site) and redirect to the index or whatever set of pages based on that.