You're a number - 584649 to be exact
Been lucky so far not to have been spammed, but you can be spammed from anything put on the public internet (including geocaching)
Search facility it quite useful
http://search.twitter.com/search?q=geocache
Which came up with :-
http://twitter.com/podcacher
If you've got an iphone/itouch then I recommend the app Twitterrific