Japanese people are buying the DSi. Lots of them. Nintendo sold over 500,000 DSi units (535,379 units by Enterbrain's numbers) during November, it's first month on sale. For comparison's sake, the DS Lite sold 550,000 units during its first month on sale in Japan.
The DSi's success has bolstered the DS platform's total sales to 24,239,590 units — a figure which includes the DS, DS Lite and the newly launched DSi.