This is a scam. The caller is NOT Apple or Walmart. Repeat: This is a scam. Do not respond in any way. Simply delete the message. At least some of these messages are directing people to a malicious site. Do not let curiosity get the best of you.
Huge numbers of these messages are generated by scammers. Huge numbers of people go into the Apple Store, Walmart, Best Buy, or whatever company the scammer claims to be. The percentage of those two groups (scam message targets, and store shoppers) which intersect is substantial. It is just math, not a sinister activity by Apple, Walmart, Best Buy, or any other legitimate business.
(Remember Venn Diagrams in math class?)
I admire a little healthy paranoia, but you might want to decrease the gain just a little bit ;^)
" Apple is looking for people to Test & Keep the New iPad3! But only the 1st 1000 users that goto http://ipad3now.co and enter code BETA will Receive it! "