Of course, being New England and all, this does not work exactly perfect. WBZ's time signal is actually 8 seconds late. Googling around discovered some discussions over whether this delay is due to the FCC-compliant talk radio time delay ("The Dump Button") or the HD signal conversion, but apparently the delay is there.
So I guess I should say that if you've ever wanted to synch your *nix computer's clock to WBZ's dual-tone signal and be 8 seconds late to everything, you can. Or as phatmike points out, add a bit to the code to subtract 8 seconds from the mark. If you really insist on being on time.
The WBZ time signal, by the way, is a radio tradition I hope never goes away. On-air personalities have come and gone, the station itself has seen some major format changes, but since the 1940s that BOOOOOOP has been there. May it always herald the top of the hour (plus 8 seconds.)