He wrote a nice note that I just had to frame.
The note reads:
THX for using the Foursquare! Remember, every check-in saves a kitten!
Friends 4 eva,
As a long-time Foursquare advocate and superuser, this note is very special to me. I later got to meet Dennis Crowley at Foursquare headquarters in New York City. I was in NYC for Advertising Week.