Updating packages after install of r-base 2.6.2: cant update rgl

Hi

I just upgraded my R from stabel/etch from 2.4.x to 2.6.2 via

sudo apt-get install r-base
which worked fine, installing all dependencies

 From R, as root, I did

update.packages()

but a number of packages packages failed to install, either for missing 
gfortran
or missing dependencies.

Warning messages:
1: In install.packages(update[instlib == l, "Package"], l, contriburl = 
contriburl,  :
  installation of package 'maptools' had non-zero exit status
2: In install.packages(update[instlib == l, "Package"], l, contriburl = 
contriburl,  :
  installation of package 'mvtnorm' had non-zero exit status
3: In install.packages(update[instlib == l, "Package"], l, contriburl = 
contriburl,  :
  installation of package 'lmtest' had non-zero exit status
4: In install.packages(update[instlib == l, "Package"], l, contriburl = 
contriburl,  :
  installation of package 'multcomp' had non-zero exit status
5: In install.packages(update[instlib == l, "Package"], l, contriburl = 
contriburl,  :
  installation of package 'cluster' had non-zero exit status
6: In install.packages(update[instlib == l, "Package"], l, contriburl = 
contriburl,  :
  installation of package 'KernSmooth' had non-zero exit status
7: In install.packages(update[instlib == l, "Package"], l, contriburl = 
contriburl,  :
  installation of package 'mgcv' had non-zero exit status
 ...

OK, I installed r-base-dev to get gfortran and other dependencies, then 
tried
update.packages() again.  This time only rgl failed, complaining about 
missing X11:

trying URL 'http://probability.ca/cran/src/contrib/rgl_0.77.tar.gz'
Content type 'application/x-tar' length 803692 bytes (784 Kb)
opened URL
==================================================
downloaded 784 Kb

* Installing *source* package 'rgl' ...
checking for gcc... gcc -std=gnu99
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... no
checking for suffix of executables...
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc -std=gnu99 accepts -g... yes
checking for gcc -std=gnu99 option to accept ANSI C... none needed
checking how to run the C preprocessor... gcc -std=gnu99 -E
checking for gcc... (cached) gcc -std=gnu99
checking whether we are using the GNU C compiler... (cached) yes
checking whether gcc -std=gnu99 accepts -g... (cached) yes
checking for gcc -std=gnu99 option to accept ANSI C... (cached) none needed
checking for libpng-config... yes
configure: using libpng-config
configure: using libpng dynamic linkage
checking for X... no
configure: error: X11 not found but required, configure aborted.
ERROR: configuration failed for package 'rgl'
** Removing '/usr/lib/R/site-library/rgl'
** Restoring previous '/usr/lib/R/site-library/rgl'

The downloaded packages are in
        /tmp/RtmpSFCuUT/downloaded_packages
Warning message:
In install.packages(update[instlib == l, "Package"], l, contriburl = 
contriburl,  :
  installation of package 'rgl' had non-zero exit status

Finally, I tried to install r-cran-rgl, but with no joy:

euclid:~# apt-get install r-cran-rgl
Reading package lists... Done
Building dependency tree... Done
r-cran-rgl is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 267 not upgraded.

Can anyone suggest what is wrong and how to fix it?

thanks,
-Michael