OpenGLBook.com is a free OpenGL programming tutorial in online book format. Click on The Book to start learning OpenGL 4.0. Several chapters contain OpenGL 3.3 compatible code samples in a sub-directory named "compatibility" in the source code listing, if you only have access to OpenGL 3 / DirectX 10 level hardware.
New Chapters are released periodically as they are completed and announced on the blog. If you wish to keep informed, subscribe to the blog's RSS feed with your favorite RSS reader.
Before you start make sure that you read the preface to get a decent understanding of the evolution of computer graphics and where OpenGL came from. The preface also lists the hardware, software, and knowledge requirements for the book, so don't skip it!