[H-GEN] programatically detecting language of UTF-8 text

[mick]

I'm working on a yahoo chat client and wish to filter out text in selected 
languages.

several days of searching and reading many documents has revealed much hype 
and propaganda and some info on coding into UTF-8 but nothing on analysis of 
strings for info like what language a string is in.

does anyone have advice on any of:
links to this info
search strings to google
example code

thanks mick