Where is the ipsw file located after downloaded via iTunes?

Mac OS X

For iPhone: ~/Library/iTunes/iPhone Software Updates

For iPod touch: ~/Library/iTunes/iPod Software Updates

(The tilde "~" represents your Home directory.)

Windows XP

For iPhone: C:\Documents and Settings\[username]\Application Data\Apple Computer\iTunes\iPhone Software Updates

For iPod touch: C:\Documents and Settings\[username]\Application Data\Apple Computer\iTunes\iPod Software Updates

Windows Vista

For iPhone: C:\Users\[username]\AppData\Roaming\Apple Computer\iTunes\iPhone Software Updates

For iPod touch: C:\Users\[username]\AppData\Roaming\Apple Computer\iTunes\iPod Software Updates