Charlie, although 3-tier architecture fits well in to the browser front-end type of apps, IMHO it's fundamental concept works well across all types of apps, including 1 and 2 tier. Even a lot of new 1 and 2 tier apps you build now will benefit greatly from implementing "logical" 3-tier architecture later on when it comes to scalibility and maintenance.

>Personally, I wouldn't go to 3-tiers unless I was developing a web app. All my stuff runs either on a LAN or WAN so I have been happy with 1 and 2 tiered solutions.