Since I started freelancing in 2005 I've always deployed my stacks myself, learning gradually.
I always felt that doing it manually (even using well-written notes) then gradually home-baked tools was a loss of time.
I looked at chef more than a couple of times, waiting for the documentation to be more available, and for feedback from people I know.
I started using chef with the opscode platform, then went back to chef-solo as it really fits my needs already.
I'm using it for client work as well as for everything behind HackerBooks (including Rails app deployment without capistrano anymore).
The consequence is that I can boot a new ubuntu instance from scratch, completely configured with the whole stack (rvm, rails 3, passenger, nginx, solr, god, the properly configured crawler, data restored from a S3-like etc) in less than 15 minutes.
I will never go back to manual sysadmin (apart from small tips) - this really fits my way of working.
But it has been a time-sink to get in :)
Hope I replied to your question properly, if I didn't, ask again!
But a large part of it (the 2/3rds) was a learning exercise around chef and vagrant, which wasn't necessary to the project.
Of the remaining third, I've got around 70% for data processing in general and 30% on pure front-end code and design.
I really wanted to learn how to deal with sysadmin in a more productive fashion, so I took the plunge :)