Or give this a try:

tell application "Safari"
activate
set theURL to URL of document 1
end tell
do shell script "open -a Firefox.app " & theURL

Edit: note that this script doesn't require you to have made Firefox your default browser.

Last edited by dkmarsh; 01/24/12 12:41 PM.

dkmarsh—member, FineTunedMac Co-op Board of Directors