If a site is designed with CSS it is pretty easy to modify the css to have a specific set of formatting for mobile... to not show certain things when viewed on a mobile. It uses the same site but displays it differently.
I think that is a much safer and wiser approach than a dedicated mobile website. .mobi was pretty much dead shortly after it started. The iphone's browser made it unecessary and since all the new smart phones are trying to beat the iphone, then they display sites fairly well too. Many smart phones display flash, but the iphone is incapable of it. It has always been my recommendation if you have flash to provide an alternative to it. An image if the flash is just graphical. Links if the flash is navigational. The best solution to this is to use SWFobject
to present Flash if the browser can handle it, or alternate content if the browser can't.
The interesting thing is whether many of the mini tablets out there (ipad knockoffs) are treated as a mobile phone or a more traditional viewer. This I am not sure of yet.... but I think I just came up with a good reason to justify me getting an Arcos tablet or some other