The included sample web site is a decent example of basic functionality. You are correct that nothing much will change in the business layer, the implementation of the BO's in the project is different but straightforward and the SF guys have done a lot of the lifting for you as far as having to worry about state.I have a few projects that have been born as desktop apps and later had a web module added with no change needed to the business objects. We also have recently done a website for a pretty big retailer that gets a lot of traffic and SF has held up very well.
Now if they could just help with cross browser compatability. I like doing "web apps" where I can tell the users to use a certain browser, a true web site that has to look nice in 8 different browsers has given me a lot of grey hairs the last few months.