- You don't need a nail clipper on your person but in your carry-on bag. Why? Because you travel with carry-on only for a longer trip which implies a manicure outside home.
- The TSA polices the US only, not the whole world - yet. Different countries may have different rules regarding allowed and prohibited items. For example the EU still have no official word on the list of what items are allowed and what are banned: http://boingboing.net/2008/04/12/eu-...o-release.html
- If you search this very forum, you find many stories of confiscated nail clippers. Just think outside of the USA.

Hope this helps.