NEC Biglobe, one of the largest Japanese ISP/portal releases iPhone app “Push-Ups Dojo” to count, record and share (of course, on Twitter) your push-ups.
I am sure that there are already many exercise recording iPhone apps. This one directly uses iPhone’s touch panel as a counting sensor. You need to touch the iPhone on the floor with your nose (or chin?) to count.
Move instruction is here.
Get Biglobe Push-Ups app 
[iTunes Store]
Our favourite trickster Kayac also made the similar one (without Twitter linkage) half an year ago.
Push-Up from KAYAC inc. on Vimeo.
Get Kayac’s Push-Ups app [iTunes Store]
Both might be inspired by a popular Japanese TV program on which athletes compete in several different exercise program. There is a replica of the push-ups switch from the program sold by Konami in Japan.
