Interesting data, Richard--and certainly reassuring for those of us whose teams have yet to register.
I've been compiling my own data as to which teams are still missing, which can be seen
here. My method was to copy the data from teams by state from 2007 (seen
here for South Carolina), compile in the spreadsheet, then compare against
this roster, which appears to show all teams registered for a 2008 FRC event. (It lines up with my spot-checks and checking of nearby regionals.) As of about 1:00 PM today, I counted 698 teams yet to register out of 1,298 teams listed from 2007.
I'll update the sheet as I get time over the coming weeks.