If you go back to the Question Room, scroll right down to the bottom (below March 2010), you'll find the rules for the questions. Originally, 30 questions were allowed each month, but then Tom got incredibly busy with his real job
, and the limit was set back to 15.
I've also noticed that the rules don't include a new one that was added at or around the same time as the drop to a 15 question limit. That is that we are asked to ask the question first. Put any needed explanation after the question. And try not to ramble on (that one almost kills me -- I don't ramble; I write books!