I wrote up an article on Thread#raise, Thread#kill, and timeout.rb that 
I hope can start making the rounds. Long story short, neither 
Thread#raise nor Thread#kill is safe to use, and as a result all 
libraries that call them are also unsafe (including timeout.rb, net/*, 
and many other libraries in the wider world).

Have a look, add comments, discuss. Hopefully we can find a way to fix 
this, because it's going to hold Ruby back until we do.

http://headius.blogspot.com/2008/02/rubys-threadraise-threadkill-timeoutrb.html

- Charlie