March Madness Day 1: CBSSports.Com Serves Up 2.8 Million Hours Of MMOD To 2.7 Million Users’s Jason Kint told us the online numbers were well ahead of last year and now CBS (NYSE: CBS) has released the internal stats to back that up: NCAA March Madness On Demand drew more than 2.7 million unique users during the first day of the men’s basketball tournament, up 56 percent over the 1.75 million that showed up for tip-off last year. As you would expect, the amount of live streaming audio and video rose as well, up 65 percent to 2.8 million hours from 1.7 million. Even the “Boss Button ” — this year a spreadsheet-like ad from Comcast (NSDQ: CMCSA) — drew 1.5 million clicks. didn’t break out the amount of audio and video.

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In addition to its third-party partners including YouTube, Comcast, MSN and AOL/Bebo, CBS Interactive has gone all out with marketing across 18 of its own sites. Stopping by this morning for a news story brought up a large interstitial promo; CNET even did a how to watch March Madness video. CBS Sports and CBS Radio are promoting on the air.

iPhone: The MMOD app is the number one paid app in the iPhone app store but CBS is not releasing any sales numbers. The $4.99 app allows iPhone and iTouch users with WiFi access to watch any of the 63 games live or on demand; those connecting through AT&T (NYSE: T) on 3G can only get live streaming audio.