beta0 lmer (R-forge version)

Dear,
I would like to know the meaning of the beta0 of a fitted lmer-object  using
the lme4 package from R-Forge version '0.99999911.0'

Example:
data(Orthodont,package='nlme')
library(lme4) #R-forge!
mot<-lmer(distance ~ Sex + (1|Subject),data=Orthodont)

mot at pp$beta0


Kind regards

Ulrich Halekoh
Associate Professor
Email: Ulrich.Halekoh at agrsci.dk
Aarhus University; Denmark