Since its launch in May, Wolfram Alpha's code base has grown by 52%, over 2 million lines of code. Also, nearly 50,000 groups of changes have been manually added to the data repositories.
One of the areas of improvement is Wolfram Alpha's linguistic processing. Often, it has the knowledge but doesn't understand the question. From Wolfram:
"It’s very interesting to see the kinds of queries that come into Wolfram|Alpha, and how they’re phrased. We’re really seeing a new human language. Based on ordinary language, but without a lot of its niceties. Probably closer to the way people think internally."
http://blog.wolframalpha.com/2009/08/20/what-weve-been-doing-this-summer/