Export akima grid with gdal

Hi all,

I have gridded some data using akima's
interp.new() function.  I now want to export to
something that ArcGIS can read directly.  I was
thinking about something like a geotiff, or a
simple bil.

How do I export this akima list object using gdal?
 In know that I have to convert the list to a
spatialgrid but I just cannot manage it.

thanks,

Phillip J. Allen
Geochemist.