And that is part of the reason we don't do it - too few people understand (or agree on) what it means.
There are a little over 2000 topics posted here at the moment, that mention "virtualization" or "EC2" or "GAE" or "cloud" in the topic somewhere. I am sure I could widen the search and get a few more (e.g. add in Heroku and you will find another 13 topics). However they probably don't belong in the same forum - EC2 might work within "Virtualization", but the opposite may not be true. GAE and Heroku might fit together, but are different conceptually from EC2. They all fit under that nebulous idea of "Cloud".
We have an idea we are working on that might help us solve how we group like subjects together - please be patient.