Pardon the intrusion, ladies....
I hate to be the bearer of bad news but this story is not accurate.
Snopes.com debunked the original post as an urban legend as of October 19.
The article on Snopes repeated the original post verbatum, with the following clarification (snipped for brevity).....
"However, all of the hotel representatives and employees we spoke with maintained that encoding personal information on keycards is neither a former nor a current practice, and none of the access control system providers we contacted said their hotel keycard systems are configured to allow personal information to be encoded on keycards. In any event, turning up a single case of something that might have happened in the past by mistake under systems no longer in use hardly justifies a warning like the one issued, which suggests that the practice is current, ongoing, and widespread. "
The entire story is here:
http://www.snopes.com/crime/warnings/hotelkey.asp
Adrienne