There have been numerous reports that the newly-released Apple iPhone 4 is having some antenna issues. The metal ring that forms the outside edge of the phone can essentially short out due to the conductivity of human skin when it’s held in the wrong way.
One of my podcast listeners forwarded me this link to an item on MacDailyNews that details the problem, and details a very inexpensive, unobtrusive fix. Apparently all that’s needed is a tiny piece of plastic or “scotch” tape applied to the right place and that’s enough to eliminate the issue.