Oracle recently acquired FatWire, and renamed it WebCenter Sites. It is a "web experience management" toolkit, which is similar to Oracle's existing Site Studio product -- a part of Oracle UCM, now called WebCenter Content.
After using Site Studio for years, I got pretty accustomed to it's terminology and toolkits... so looking at FatWire was initially intimidating because it was just so dang different. But, after using it for several months, I've come to the conclusion that a lot of the fundamentals are pretty similar. Pretty much everything Site Studio does is built in to FatWire, and FatWire has a few nifty extras as well.
So, for IOUG Collaborate this year, I put my insights together into a presentation: Crash Course in FatWire for Site Studio Developers:
It's not a replacement for actual training... but it does cover all the major low-level assets, and how they fit together to form a site. If you know a thing or two about Site Studio, this should help you get over the initial "fear of the unknown!"