If you need flash support, you should have a look at the current github version of this script at http://github.com/AdamN/python-webkit2png/ mentioned above. We've extend the script a few month ago.
From time to time you may want to create a screenshot of a web page from command line, for example if you wish to create thumbnails for your web-application. So you might search for such a program and find tools like webkit2png, which is for Mac OS X only, or khtml2png, which requires a lot of KDE stuff to be installed on your server.
But since Qt Software, formerly known als Trolltech, integrated Safari's famous rendering engine WebKit (which is based on Konqueror's khtml engine) into its framework, we are now able to make use of it with the help of some Python and PyQt4.
If you are in a hurry, click here to get a full-featured version of webkit2png.py.