This version of the chart will show a rise as well, just to a fraction of a degree.
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http://blockchain.info/charts/n-transactions-excluding-popularWhile those SatoshiDICE transactions are a little different than other transactions, they still cause demand for bitcoins (i.e., you can't wager on SatoshiDICE with bitcoins you don't actually own) so excluding them isn't really the right approach in determining bitcoin usage rate movements either.