As of September, 2006, port-cobalt (and just about everybody else)
was converted to use the new TODR code.  This code has sanity checks
on initialization to ensure that the time of day is reasonable on
boot.  Currently it checks for:

Filesystem time > 5 * SECYR
Realtime clock > 25 * SECYR

The code ensures that the date is beyond 1970, which should allow
ping to function.  Note that many other programs may fail on negative
date values along with ping, this also helps them.