Hadoop-tell us what you know about it?

Friends apache hadoop is in trend. An open source software framework that supports data intensive distributive applications, licensed under apache v2 license. It enables application to work with thousands of computation independent computers and petabytes of data.
It was derived from google's map reduce and google file system.
I want to do my final year project using hadoop. I dont know how to start.
Please share, if anyone is working on some project using hadoop.
Also please share what you know about hadoop, as it will be helpful for other CEans too. 😀