Okay, back from the beach. As I kind of suspected the reader’s suggestion that the Feds came up with the 555 prefix because of that song is not true. Some e-mail:

. . .is actually a real number; it’s directory assistance. The “Federal law,” aka “Jenny’s Law,” sounded like nonsense, and sure enough [See Wikipedia] No mention of Leviathan reacting with uncharacteristic agility to a Tommy Tutone lyric.
It is, however, against the law to send police to “123 Fake Street” on false pretenses.

And:

I’m from the disco era (yay!), and I remember dancing to a song called 777-5377. Don’t remember the artist, but it did have a catchy thumping beat to it.

And:

Hi, Jonah;
Someone may have already alerted you to this, but your reader’s update is incorrect – the Hollywood “555″ prefix predates the Tommy Tutone song by quite some time.
Evidence: If you’ve ever seen the Mystery Science Theater 3000 episode “Riding With Death”, there is a scene which features a cutaway to a note left on a desktop with a phone number prominently scribbled on it, bearing the ubiquitous prefix. The movie was, in fact, cobbled together from two separate episodes of the TV series “Gemini Man”, starring Ben Murphy, which aired originally in the mid-1970s.
Of course, as Tom Servo observed, the number was Alan Smithee’s.
Enjoy the beach.

And:

See and [here].
No mention of federal legislation. According to the first link, the 555 prefix is in active use, but 555-0100 to 555-0199 is reserved for fictitious use (see for who has 555 numbers).

The other fifty-plus e-mails on the subject seem to repeat the above quite a bit.