Interestingly, I was the one who lobbied Twitter (more specifically Matt Sanford of the search team) to make '$' a valid stop character for searching on summize/twitter search. You've been able to search $TICKER for 2-3 years now. The only thing Twitter has done now is linkified them like hashtags, and they only link to a twitter search of that ticker... so nothing really interesting yet.

I've also linked $TICKER from TweetGrid for as long, except my links go straight to StockTwits: e.g. http://tweetgrid.com/grid?l=0&q1=%24AAPL