Prediction interval values

Hello!
Sorry for posting this here, but I did not get any answer at the R-help list. In brief,
I wonder how can one get upper and lower limits of a prediction interval
-- exact values, for random-effects? They are shown on caterpillar plot using ranef() with
argument postVar=TRUE, but I would like to know them. A while ago, some
discussions were opened on "Confidence Intervals for Random Effect
BLUP's", but the answer was never clear:
http://www.mail-archive.com/r-help at r-project.org/msg04820.html

Thanks!
PM