I don't object strongly, but since locks are "supposed" to be held for 
short amounts of time, a timeout shouldn't be that useful, and when 
people really need it they can put it together with a condition 
variable. Timeouts also interact poorly with condition variables: you 
can time out the initial acquire, but if you wait on a condition there's 
no place to put the timeout on the reacquire.

Given that it's hard to pick a timeout in most cases anyway, I think 
it'd be a much bigger win to figure out thread interruption. (Yes, I 
know that's hard, and that I promised to do it a long while ago and 
never got around to it.)

That said, I have no objections at all to adding an internal timeout 
ability for use by Condition.wait, and if you're still enthusiastic 
about adding the timeout given the above argument, I won't block you.