R help - Nov 2010 - How to obtain prediction intervals for random effects?

Hello!
I wonder how can one get upper and lower limits of a prediction interval 
-- exact values? 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