On 03-may-2012, RelEng infrastructure processed over 40,000 test jobs in a 24 hour day. 40,207 to be precise.
For comparison, 30,000 test jobs a day was a big milestone for us only 5 months ago (09-dec-2011). The milestone of 20,000 test jobs a day was only two months before that (19-oct-2011).
The initial value of ~100 for May2007 is a complete guess on how many test jobs our 2?3? test machines could handle back then when I first started at Mozilla, in between starting to bring up unittest automation, all the tree closures, and needing to rebuild-firefox-as-part-of-tests. Even if the initial value is slightly wrong, the order of magnitude is right. The gap since from 2007-2010 is because we did not have any metrics in place.