some tags are ready only. - so can't store a virus
some tags are only 96 or 128bit, - which is only 12 ~16 bytes (hardly
enough to store a virus)
some tags have 48, 64 and 128bit encryption (so the encryption has to be
cracked 1st)
most RFID tags are small memory size and not enough to hold a virus.
Contact smart card which have large memory HOWEVER may be able to hold a
virus.
The Wallmart / Kmart tags in the article are typically 12~16bytes
Sounds futuristic
Joe