Activating html help in R 2.10

After reading the news about the release of R 2.10 I expected that 
typing for example ?cut would automatically open a web browser.  But I 
don't see any difference in how help is displayed under Ubuntu Linux 
(karmic).  How does one activate the new dynamic html help?

Thanks
Frank

platform       x86_64-pc-linux-gnu
arch           x86_64
os             linux-gnu
system         x86_64, linux-gnu
status
major          2
minor          10.0
year           2009
month          10
day            26
svn rev        50208
language       R
version.string R version 2.10.0 (2009-10-26)

Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University