What about AT&T or Verizon retail stores, can you purchase apple+ care through the AT&T or Verizon retail store?
You CANNOT buy AppleCare+ through AT&T or VZW (though there have been reports of Spring customers being able to). From Apple, you can buy it at time of purchase or up to 30 days after, but you will have to take your phone to an Apple Store for inspection if you choose the latter.
I put together a pretty extensive comparison of various protection plans a few weeks back.
AppleCare+ vs. VZW Extended Warranty vs. Bb Geek Squad