No substitute for experience...
I've been an architect for 5 years (having been a SysAdmin and DBA for the 10 years before that) and I don't think I could define it either. One of the things that goes to make up a good architect, IMHO, is experience. It's all about taking what you've done before and applying it to new and different situations. I've come across people who went straight from a particular company's graduate recruitment programme into their architecture practice with no 'practical' experience in between, and they were perfectly fine architects.
But all the best architects have a number of years of experience under their (almost entirely male) belts and can look at new technology and see how it will fit into existing infrastructures to "add value" (ugh). I guess that's the key, isn't it? As long as new stuff keeps getting pushed out there by the vendors, we will always need architects to do something with it.
Hey! It's all Microsoft's fault! I knew I could work the argument round to that somehow...