Once you are feeling better try doing a pushup on your fists this takes the pressure off of your wrists. I broke down and bought the perfect pushup handles at Dick's sporting goods and I haven't had any wrist problems since. I was skeptical, but they really did make a big difference.
i have the Ultimate Gym (???) thing they've been advertising on TV as of late; handles for pushups as well as a pull-up bar that doesn't need any installation, just friction. i HIGHLY recommend it! the pushups ive been doing are a world of difference if only because the extra range of motion i get...you can go 'deeeep' with handles.
i keep telling myself i'm going to do the 100 pushups, but i keep doing the initial max-rep test every night instead of looking at my intervals.
oh, hand placement is key...make sure your arms are square with your shoulders, you'd be amazed at how easy it is to sprain a wrist when youre not square, fatigue sets in and you start cheating.