Don't just implement it, and then discover to your horror that you've put up a roadblock. Here's an easy test. Submit a typical URL to Infoseek or AltaVista. If you see the page appear in a few days, you're probably okay. If not, you may have problems.
Frames are another nightmare.
If you have a site that uses them, really consider getting rid of them. If you are building a site or redesigning, drop the idea of frames right now. In many cases, frames are unnecessary navigational crutches. They always pose significant problems for search engines. It is simply poor marketing to use them, in many cases.