That's over 280Gbps sustained over that period, probably peaking to more than 3x that amount!
Fortunately for ISP's they are using the Akamai network for updates :)
For various reasons I downloaded it three times in the two days following the release, and each time it consistently filled my downlink (at home, 15Mbit/s, and at work 20Mbit/s). The CDN definitely did a nice job.
They also released lots and lots of "minor" updates for different applications (iWork = 1GB, iLife = 3GB, OS X Voices = 1GB, ...), so the number is actually higher than that.
Heh, that's the rounding error in a Windows release.
Like the vista release?
Microsoft basically sells 20M Windows 7 licenses pee month (driven almost entirely by PC sales) so the Apple figures are actually quite impressive (given Apple's smaller base).