writing to .xlsx

Dear r helpers;

I'm interested in reading from and writing to large .xlsx files fairly
regularly.  (Why, the naysayers may ask - and the answer is basically
colleagues and clients who prefer that format). I've tried out the
XLConnect and xlsx libraries, but the java implementation they use just
takes too much RAM for the files I'm working with.

gdata leverages perl and works really well for reading in those files, so
half the problem is solved for me! I don't see anything in the
documentation about writing .xlsx, though. Is anyone aware of any libraries
or clever solutions in R that would get the job done for me? I see a couple
packages on CPAN for writing an xlsx, so it's been done in perl; perhaps it
would be easy to run that from R? I don't use perl myself (yet?).

Looking for recommendations.

Best

Ben Caldwell