R help - May 2011 - glmnet_1.6 fails to install due to unsupported Fortran 90 compiler

Hi,

if I try to install glmnet, the installation fails with:
> install.packages("glmnet",dependencies=TRUE)
trying URL
'http://mirrors.softliste.de/cran/src/contrib/glmnet_1.6.tar.gz'
Content type 'application/x-gzip' length 522657 bytes (510 Kb)
opened URL
=================================================downloaded 510 Kb

* installing *source* package ?glmnet? ...
 This package has only been tested with gfortran.
 So some checks are needed.
 R_HOME is /usr/lib64/R
Attempting to determine R_ARCH...
R_ARCH is 
Attempting to detect how R was configured for Fortran 90....
    Unsupported Fortran 90 compiler or Fortran 90
    compilers unavailable! Stop!
ERROR: configuration failed for package ?glmnet?
* removing ?/usr/lib64/R/library/glmnet?

The downloaded packages are in
        ?/tmp/RtmpBeEzO5/downloaded_packages?
Updating HTML index of packages in '.Library'
Warning message:
In install.packages("glmnet", dependencies = TRUE) :
  installation of package 'glmnet' had non-zero exit status


I have a gentoo-linux and gfortran belonging to gcc-4.5.2:

root at moose:/root(46)# gfortran -v
Using built-in specs.
COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.2/gfortran
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.5.2/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured
with: /var/tmp/portage/sys-devel/gcc-4.5.2/work/gcc-4.5.2/configure
--prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.2
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.2/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.2
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.2/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.2/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.2/include/g
++-v4 --host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu
--disable-altivec --disable-fixed-point --without-ppl --without-cloog
--disable-lto --enable-nls --without-included-gettext --with-system-zlib
--disable-werror --enable-secureplt --enable-multilib
--enable-libmudflap --disable-libssp --enable-libgomp --enable-cld
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.5.2/python
--enable-checking=release --enable-java-awt=gtk --enable-languages=c,c
++,java,objc,fortran --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu
--with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.5.2
p1.1, pie-0.4.5'
Thread model: posix
gcc version 4.5.2 (Gentoo 4.5.2 p1.1, pie-0.4.5) 

Any hint is appreciated.