Apparently, I've been having the same problem because I'm here, but I honestly can't blame it all on the 6.0 Update (which I downloaded Wednesday); and yet I don't know where to place the blame. I was having this slow or delayed updating/installing problem for about 2 weeks prior to even realizing there was an Update available. However, when I did download the Update, the installation/updating process for apps got unbelieveably worse - for small and large apps. I KEPT getting "Cannot connect to iTunes Store" and/or "App is unable to install, try again later" or something to that affect.
My instinct/fear will not let me reset my phone, so I decided to reach out to the support communities for a alternative solution. While reading around for solutions for these messages, I guess I found my own?! I logged out of iTunes on my phone and restarted the whole phone. Once it was back on, I got an "App is unable to install" prompt on an app that had stalled in "Waiting..." mode from the moment I bought it on yesterday. I pressed ok and then went back to the App Store to attempt to reinstall the app again. This time, I was prompted to log back in to iTunes. Once I did that, it installed with no problem...at the rate it would have 2 weeks prior.
I did this in a 3G area, with no wi-fi and not hooked up to internet through a computer. It works fine when wi-fi and/or internet connected. Now whether or not that is a fix, I don't know?! But it's working for the time being; if not, I'll most likely try 'jvicks' fix if it happens again.
