An update to: http://www.wowinterface.com/downloads/info17691-HideChatButton.html

A button to hide the chat window.

This button will hide the chat interface. It hangs out in the lower left corner, and a click will toggle the chat panels on or off.

Chat notification support. Indicators show talking.
Keybind support! You can now bind a key to show/hide chat.
Move the button! Right-click-drag to move the button.
Mouse wheel support.
CTRL-click to reset button defaults.
SHIFT-click to toggle Keyable.
ALT-wheel to adjust button alpha.
Slash command added.
Hide/Show preference saved when logging out

Chat Notifications - The button will now show a colored letter indicating what channel talking is happening on, so you can tell if a whisper or guild chat etc., has happened. This only appears when chat is hidden, and will appear while the frame is faded as non-keyable.

Keybind Support - You can now add a keybind to show or hide the chat frame. (It's a single toggle, not one to show and one to hide.) Look in esc > Key Bindings > Hide Chat Button to set.

Mouse Wheel - The mouse wheel will now let you show or hide the chat.

Keyable - The chat box by default will show or hide an edit frame to allow you to type when you type / or when you hit enter. The keyability option will now show a hidden chat box when you hit enter or type /, or not, you choose. The chat button will fade out when it is not keyable. When it is not keyable, you can still type / or hit enter to show the edit box, allowing you to still type commands even, while keeping your chat hidden. This was added because it was incredibly annoying to try to use / commands with a hidden chat box.

SHIFT-mouse wheel will toggle keyablity.

Alpha Adjustment - You can now adjust the button's alpha state by using ALT-mouse wheel.

Slash Commands - You can toggle visibility with /hcb, or you can reset to defaults using either /hcb reset or /hcb default.

Hide/Show Preference Saved - The window will retain it's visibility per-character, so when you login you don't have to click the button every time.