This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Because somebody thought hashtable is all one word? Because somebody misunderstood the convention about subsequent words having capital letters? I think there probably is no deep mysterious reason for it.