At this time the future of Caller ID spoofing is unknown. It is currently not illegal to spoof Caller ID, as long as you are not a telemarketer, but this may change in the future. Various bills were introduced in 2006, none of which have been passed, but they were all targeted at using Caller ID spoofing service for fraudulent means. In June 2007, The Truth In Caller ID Act of 2007 was passed again in the House of Representatives, passed in a Senate committee, and is awaiting hearings by the Senate now.
Caller ID spoofing in its nature, cannot be completely stopped, as millions of businesses across America rely on it in one form or another. Also, law enforcement officials and government agencies (think FBI and CIA) have been known to use Caller ID spoofing to protect their identity for various undercover situations. If any laws against Caller ID spoofing were enacted, it's likely that they would not shut down the Caller ID spoofing industry, but place restrictions on how the service can be used, which at this time is not regulated.
Even the Truth In Caller ID Act of 2007 doesn't actually outlaw Caller ID spoofing, contrarty to popular belief. The Truth In Caller ID Act of 2007 is mainly set out to strictly prohibit fraud and harassment through Caller ID spoofing. The bill also places responsibility on the individual using Caller ID spoofing to use spoofing within the law and DOES NOT prohibit companies from providing commercial Caller ID spoofing services.
Canada has never questioned Caller ID spoofing services at this point, and if any sort of laws were passed in the United States, this would not affect Canada.