SIRIUS has extended its lifetime sub offer from the end of Jan 2006 to July 31st 2006..
You can take a look at the new updated "Plans & Services" here
SIRIUS has also added details to the Lifetime plan:
"Subscribe for the lifetime of your radio! Pay $499.99 once, forget about bills altogether, and enjoy SIRIUS for a long, long time to come. Plus, you can now transfer your lifetime subscription to three additional radios for $75 per radio. (Offer ends July 31, 2006.)"