This excerpt taken from the SIRI 10-Q filed Nov 12, 2008.
Consumers could steal XMs service.
Like all radio transmissions, the XM radio signal is subject to interception. Pirates may be able to obtain or rebroadcast XM radio without paying the subscription fee. Although XM uses encryption technology to mitigate the risk of signal theft, such technology may not be adequate to prevent theft of the XM radio signal. If widespread, signal theft could harm XMs business.