I set something up that might work for you. I set up a webcam facing my daughter's crib which was hooked up to an old computer. Then I made a free account at Livestream.com
(not affiliated w/ them). You can broadcast videos online, live (but there are occasional commercial interruptions w/ free account...didn't bother me much) and anyone you choose can tune in. I only used it for myself and occasionally my wife would watch from work :)
What I did was, before nap time, I'd start a broadcast on Livestream of the webcam feed, but I'd set it to PRIVATE so no one else could see the video feed but me. (you do this in the livestream settings)
Then when I put the livestream app on my phone I could log-in and watch my baby napping, live, on my iphone. It works best if you're using wifi on your phone but it works over 3g connection too. So you can watch from a neighbor's house or even across the globe really.
It takes an initial set up of about 20 minutes and after that, you just log-in and start recording' the video and watch from your phone. You have to install the free apps on your phone and computer though...I think it's called procaster.
They also make video monitors that are quite expensive and some may come with their own iphone app to watch on your phone. I hope this helps.