My colleagues and I have been interested in model-based methods
to detect differential expression signals in microarray data.
EBarrays is an R package for empirical Bayesian analysis of gene expression data. See the developmental packages link at Bioconductor to download this package and obtain more information.
You can download the g-zipped version of EBarrays. Installation directions are here. Once installed, type demo(ebarrays) to see a demo of the package. A vignette is also available once the package is installed. You can download that vignette here.