70 characters is a bit of a pain. Isn't ExpressionEngine's default 100 characters?
We're not actually using Expression Engine for the forums Jonathan - it's PunBB. At this stage, I'd say 70 characters should be enough for a title - you don't need to explain the entire question there ;)
Hmm. Thanks for correcting me on EE. But regarding the 70 character thing...
As a random test, I just went to the EE forums and looked at the first page listing of their latest threads in their Technical support forum. 3 out of 30 thread titles were over 70 characters -- and none of them are mine!
You're right that you don't need to explain the entire question but 10% of the time I probably would wish to use a title longer than 70 characters and here's why.
I don't know about you but when I visit a forum, I'm often looking for an answer that's already there and quite often words in the title are key to finding the appropriate thread. For me, thread titling is as much about ease of being found by the community later as it is about me getting an answer right now. Not having a limit helps this.