There are a couple of articles that say ultrasensitive PSA above .02 after
RP is a bad prognasticator.  Witherspoon and Doherty are the authors of
the articles and Dr. Strum cites these articles often.
I am 3 years post RRP and my ultrasensitive PSA's have ranged from .035 to
.070.  My pathology post-surgery was cancer contained and clear margins.
My preop PSA was 5 and Gleeson 6.  
Not getting to less than .02 has been a concern but my doc says there are
alot of post surgery patients with my numbers.

Buttercup's Dad wrote...snip...

The us PSA test provides at least 2 pieces of additional information
for post_RP men or men using HT.  First, the lower your PSA goes after
RP or during HT (or after RT for that matter), the better the
prognosis.  Second, it provides earlier visibility to recurrence and,
consequently, more time and datapoints to plan and estimate doubling
time respectively.  Dr. Strum and a number of others recommend its use
in these settings.  Using the same lab and routine (time of blood draw,
etc.) helps to minimize variation.  Although the test reads to 3
decimal places (e.g. 0.003 ng/ml), many labs round it off to 2 decimal
places (e.g. 0.02 or >0.01 ng/ml) to further limit the effects of
variation   Of course, it's a personal choice as to how much data an
individual chooses to have, but make no mistake, there is valid data
there.  We need to keep in mind, however, that just as with the
standard PSA test, the trend is more important than any single
datapoint...Ron