Started at 30 and I'm now up to 40.
hundredpushups.com is really not working out that well though, been stuck on week 4 for so long because its so tough. And the first stage of week 5 is so much easier than week 4, it doesn't make much sense.
Start by doing wall push-ups, it's the same as a regular push-up just much easier since so much less weight is applied. Start by seeing how many you can do in one go. Build up until you can do 100 in a row.
Once you can do that transfer to the floor, do as many as you can and then finish the 100 by doing wall push-ups.
This can also be for anyone, start on the floor, do as many as you can, then do wall push-ups to finish, will really help build an endurance base while your strength builds up. And forget about knee push-ups they don't really do anything.