While the Raspberry Pi does provide a superb picture over hdmi, there are a lot of scenarios where one might not need a display, and connecting remotely via VNC will suffice. For instance, any programming could be done remotely, while still having access to the physical hardware. It's also particularly useful when the TV is in use and getting it back to "play on" isn't an option.
EDIT 29/04/2012: I've had a done a bit of a clean-up on my blog, creating separate pages for specific tutorials, keeping the main page free. You can find the VNC guide here, or click on the tab at the top of the page.