Minecraft 1.7.3 snapshot 13w48b is out and the official download of 1.7.3 is coming soon. This update includes lots of bug fixes e.g. the unsafe minecarts bug and some streaming bugs. It also adds new shaders, called Notch shaders, which gives the textures a more retro/”blocky” look.
To get snapshots, open your Minecraft launcher and press the “New Profile” button. Call it “snapshots” and check the box saying “Enable experimental development snapshots”, then click save. To switch to the normal version, you can select it in the dropdown box found at the bottom left corner of the launcher. Enjoy.