earthdistance results seem to be wrong.

I'm running PostgreSQL 8.0 beta 1.  I'm using the
earthdistance to find the distance between two
different latitude and logitude locations.
Unfortunately, the result seems to be wrong.

Here is what I'm doing:
select
earth_distance(ll_to_earth('122.55688','45.513746'),ll_to_earth('122.396357','47.648845'));

The result I get is this:

128862.563227506

The distance from Portland to Seattle is not 128862
miles.