Changing Captured Screenshot's Defult File Type In Snow Leopard

Every now and then, I need to capture screenshot on my computer to create how-to documents for my users. I notice that Mac OS X captures the screenshot into PNG format by default. I prefer JPG to PNG because of the smaller file size. Here is how to change default file type of screenshots in Mac Snow Leopard. 

$defaults write com.apple.screencapture type jpg

Then, U need to restart the UIServer.

$killall SystemUIServer

Now take some screenshots by shortcut (Command+Shift+3) and U will find captured jpeg files on Desktop.