Does this seem like an effective plan for improving my push-ups count?

A friend of mine recently sent me a link to the website http://hundredpushups.com/

The site claims that by following their program, in 2-3 months you can train up to doing one hundred push-ups. Now, this seems a little shaky to me. Going from maybe the 20 I can do now to 100 in a few months sounds a bit unbelievable.

I must say, however, that having done the first two days of the plan, my arms hurt more than they ever have from other workout methods I have tried. But on to the question:

Those of you who are in-the-know on strength training, does this plan seem to be worth a shot? Or would I be better served by just doing the typical “pushups to exhaustion 3 times a week” method? Does it seem feasible that I could get up to 100 push-ups if I followed the plan, or is that a bit unrealistic?

I’m not an expert but I’ve been on this program for a few weeks already. My perspective is:
I’ve definitely improved the total I can do, but I think it’ll take a lot more than the six weeks mentioned in the website.

It has taken me two repetitions of week 2 before I could manage week 3 day 1. The jumps from week to week are pretty high.

Mrs GSV has noticed some improvement in my biceps and pecs though, so there are… benefits.

My suggestion: Do some crunches in the rest periods between sets. But do it in the “run your hands up your leg to the knee” style so you don’t tax your arms.