CI for Ratios of Variance components in lme?

My apologies if this is obvious:

Is there a simple way (other than simulation or bootstrapping) to obtain a
(approximate)confidence interval for the ratio of 2 variance components in a
fitted lme model? -- In particular, if there are only 2 components (1
grouping factor). I'm using nlme but lme4 would be fine, too.

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
 
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box