John Marstall has written this article called “The Easy Way to Get iOS Screenshots on Your Mac” on his web site The IconMaster.
He admits to using Dropbox to send images back to his Mac from his iPhone, but found it to be too difficult to get to individual photos. (Screenshots)
After making sure that all devices have Photo Stream turned on, he locates the Library folder in the user’s account on the Mac. (Hold down the option key then click on the Go menu and select Library.) Navigate to iLifeAssetManagement>assets>sub. Do a search for “png”and select “Portable network Graphics image” from the popup. Save the search and put it on the Dock.
Once all the steps are done any screenshots made on an iOS device will show up almost immediately on the Mac. (Retina iPad ones are large and will take a little longer.)
For complete details with illustrations go to: http://theiconmaster.com/2012/04/the-easy-way-to-get-ios-screenshots-on-your-mac/
(Imagine my amazement when I followed his steps an found 6,664 images in the above folder. Screenshots all the way back to December 2003. Which was at least 2 Macs ago. WOW!)