Painless way to install a new version of R?

Andrew Gelman recently lamented the lack of an easy upgrade process for R (probably more relevant on Windows than Linux). Does anyone have a good trick for doing the upgrade, from installing the software to copying all the settings/packages over?

This suggestion was contained in the comments and is what I've been using recently. First you install the new version, then run this in the old version:

#--run in the old version of R

setwd("C:/Temp/")

packages <- installed.packages()[,"Package"]

save(packages, file="Rpackages")

Followed by this in the new version:

#--run in the new version

setwd("C:/Temp/")

load("Rpackages")

for (p in setdiff(packages, installed.packages()[,"Package"]))

install.packages(p)