The basic idea is that the president can cause who and whatever it wants to be "surveyed" without a court order.
Recently I came across this tidbit related to Hepting vs. AT&T which involves FISA.
An AT&T technician named Mark Klein attested in 2002/2003 AT&T allowed the NSA to install a Narus supercomputer in its San Francisco office in order to monitor internet traffic including internet-based telephone calls.
Klien was interviewed by PBS's Frontline in 2007.
Basically he describes that the NSA put a "splitter" into the main AT&T internet feed being switched the Folsom Street office in San Francisco. The "splitter" splits off an optical copy of all the internet traffic and routes it to another floor in the Folsom office with Klien, an union telecom man, has no access to. (The union contract with AT&T basically guarantees all telecom techs access to all the equipment - but this extra room was an exception.)
Klien says of the internet traffic in the room the NSA was "... basically sweeping up, vacuum-cleaning the Internet through all the data, sweeping it all into this secret room. "
Klien describes the NSA hookup as "the Quantico Circuit" - Quantico, VA is the headquarters for the FBI.
In the end the EFF sued AT&T and the federal government for violating privacy laws - this was in 2006.
Its taken nearly six years for this case to wind its way through the courts - and it not over yet. The Ninth Circuit Court of Appeals recent decision from this Engaget article says that AT&T and other telecoms are immune from lawsuits related to privacy.
More interest is this (from the same Engaget article). The Ninth Circuit Court of Appeals "... gave the go-ahead for a separate suit against the NSA, former president George W. Bush, senior members of the Bush administration and President Obama for using AT&T's network to conduct "an unprecedented suspicionless general search," according to the filing."
What does all this say about our modern world of cell phones, PDA, iPads and the rest?
Basically that our government (through the previous and current Administration) have no problems surveying the general public in the name of security.
And, apparently, most of us either don't have a problem with it, don't know or simply don't care.
No doubt there are many, many Narus links installed all over the country, if the not the world, funneling data to the NSA for processing.
At the same time apparently these techniques work as there have been to subsequent terror attacks on the US - though "work" here may be a misnomer because in a variety of cases (example here) local law enforcement did at least as good a job with various potential terrorists.
I recall at the end of the movie "Indiana Jones" the Ark of the Covenant is wheeled off into a giant, endless government warehouse for storage at the end of the movie. This movie was made around 1979 or 1980.
Today the data bits of your telephone call are being "wheeled off" into that same warehouse.
(No doubt the Ark of the Covenant has be destroyed to prevent anyone from thinking the Government supports a specific religion.)
Except now that warehouse is an NSA server farm with hundreds of millions of terabytes of disk space.