Earlier today, most of the morning up until around 1-2pm it wasn't working here in my area of Florida. Appears to be working ok now though. Last day or two it's been spotty until the early afternoon here.
A friend of mine, my advisor at my college that I attend, was having issues receiving messages yesterday and last night. I then was trying to text her late last night and it was not showing up as iMessage. She told me this morning that she turned off iMessage in order to receive and send text messages.
In case people didn't know, if you're sending an iMessage and it's not going through and you want to make sure it sends, press and hold on the text and it will give you the option to send as a regular text. Sometimes if you just hit send and minimize or close it, it won't send at all.
Apple released an official statement tonight to the Wall Street Journal. The iMessage problems will be fixed with an upcoming software update. They've been testing 7.0.3, so I suspect we'll see that rather quickly.
“We are aware of an issue that affects a fraction of a percent of our iMessage users, and we will have a fix available in an upcoming software update.”
If you're having a problem maybe you should just shut off iMessage until a fix is supplied. Then all your messages should go through your carrier. Of course this also depends on what text plan you have. My text plan is unlimited with AT&T so it won't cost me anything additional.