WAL shipping to two machines (PITR)

We currently have a PITR solution in place that is facilitated via WAL
shipment.  This is implemented on 13 databases, where the two primary
machines which contain the production databases and the PITR machine are
physically located in the same facility.

We now want to add a second PITR machine that is in a remote location.
The question is, what is the best solution for such an effort?  We've
considered shipping the wal files to both locations, but the concern is
that if one fails, how do we maintain the other?

We've considered rsync the shipped wal files, to the remote machine, but
that entails some delicate timing issues.

Any suggestions, pointers would be greatly appreciated.

--
Until later, Geoffrey

Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety.
  - Benjamin Franklin