Update: Adam Savage retracted this statement and says that the segment wasn't killed by TI or the credit-card companies.
Check out the first two minutes of this clip of Mythbusters' Adam Savage telling the folks at the HOPE hackercon about how the Discovery Channel was bullied by big credit-card companies out of airing a program about how crappy the security in RFID tags is.
Arphid Watch: Mythbusters and RFID