I shoot RAW for everything. Usually Raw+JPG. JPGs for displaying on site, RAWs for producing the finished product.
Last event we shot saw 53,680 images delivered to our booth by three photographers. We kept 75% (or 40,536) for sale. That's about 600GB worth of files.
A couple of TB HDDs per event is cheap. CF cards are cheap (we have a couple of hundred 4GB cards). Our RAW processing workflow is faster and higher quality than JPG alone.
I switched to shooting RAW when I switched from the D1x to the Canon 1D back in 2003. The original Canon 1D out of camera JPGs were bad - heavy shadow tones, a funky green cast. Then I saw the results possible with CaptureOne and RAW files and I was sold.
Since then I have switched to Bibble for it's flexible, user creatable work queues, but I still shoot RAW for everything - landscapes, weddings, portraits and even sports. In my view, if it's worth taking a picture of, it's worth having a file with the most information and flexibility possible.