Speed of Swallow
It may not know the speed of a general unladen swallow (try "what's the speed of an unladen swallow") but it does at least give a reason why. Get more specific and click on the link for a European swallow, and it will give you the answer - even noting Monty Python as the question source.
For most people, Wolfram Alpha is going to be of limited use. Sure it can tell you the weather with pretty graphs and a few other stats, but really it's best for a set of technical questions that combine interpretation, calculation and display of data. Hopefully though it will keep improving as I find it better than Google for certain queries.