All right, now things are starting to get serious. I'm now doing 105-120 push ups per session, with about 60-120 seconds of rest time betweem sets. I'm occasionally taking slightly longer rests between the penultimate and final sets, mostly because my arms feel like they've been tenderized. Slight cause for concern there, but not too bad overall.
As a wise man once told me, "true strength is balance through the body". So, to avoid having a massive chest, bad posture and weak legs, I've been rolling in a fairly comprehensive back/shoulder and ab workout alongside my push ups. It's amazing the quality workout you can get with $5 elastics and a Swiss ball. A nice side effect of the 100 push up challenge is that its motivating me to improve my overall fitness, not just my ability to push things.
On to week four. Over halfway there. Will I do it? Damn good question.