definitely true. you can usually turn it off in most twitter clients though. (for example in my plixi postings, there's no meta data on location, but there is on other people's (e.g. -see the small map on the right here - http://plixi.com/p/41275963 its not even hiding the info!) Actually an even bigger problem is that some twitter clients actually put your latitude and longitude of your last tweet into your twitter profile info. I find this the most shocking cause you don't even need to find a picture to dig the info out of. it lists it right in your page. I pointed this out to female artist on this site who's my twitter friend by pointing out I know where her friend's house is she was tweeting from and she freaked out... :-P

good thing I don't have twitter, but then again isn't the idea of twitter to get people to follow you ;-p