OK, when I got home, I looked at my PRS-650. It was sitting on the standby screen with a warning of low battery. I woke it up and the charge indicator was sitting at no bars. I plugged it into the monoprice charger with my generic cable and it started charging. I came back an hour later and unplugged the charger. The charge indicator showed a full charge with all bars filled in. I don't believe it was a 100% charged though, so I put it back on the charger and will unplug it before I go to bed.
I am a little concerned that I believe that when I looked at it this morning, it indicated ~75% charge but when I looked at it tonight it was almost totally discharged. Sitting in the sleep screen should not have used that much battery. I will watch it to see if I have a problem.
To get back to the original posting, the particular chargers I received will charge both my iPhone 4 and my Sony PRS-650 reader.
This is the cable I purchased on e-bay. It is a $1.50 shipped. It is a generic cable.
http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWNX:IT