httr 0.5 is now available on CRAN. The httr packages makes it easy to talk to web APIs from R. Learn more in the quick start vignette.

This release is mostly bug fixes and minor improvements, but there is one major new feature: you can now save response bodies directly to disk.

library(httr)
# Download the latest version of rstudio for windows
url <- "http://download1.rstudio.org/RStudio-0.98.1049.exe"
GET(url, write_disk(basename(url)), progress())

There is also some preliminary support for HTTP caching (see cache_info() and rerequest()). See the release notes for complete details.