In my opinion the official arduino lacks of good features. It's 2000 style kind of forum. Find details here: http://arduino.cc/forum/index.php/topic,158796.msg1189123.ht... Whereas SO with editing wiki features and a clean tagging mechanism leads to a very clean Q&A knowledge base. Which implicit builds a good API documentation.
arduino.cc is about as polished at the standard IDE. :-)
I agree that a StackExchange site for Arduino, or even "hobby embedded electronics," which could cover the BASIC Stamp and other devices, would be a much better aggregation of expertise and information.
