to do a mobil website you have to watc out for:
- scaling of course, make sure everything fit and every text is readeble.
- Flash is a problem :s
- Dont forget to try on multi mobil borswer (IE,OPERA,....)
- Do not put big images or else the load would be slow and will unscale everything.
- You can check out Microsoft best practices for mobil dev
- If your website has textbox use auto implementation, for some device is painfull to write in a mobil website
i will put some more later, hope this helps