The packages distributed with x64 Ubunty Hardy do not properly. You get the following error:
An Gramadoir: problem reading the database
at /usr/bin/gram-ga.pl line 339
I'm don't know perl but when using strace it looks like the persistence format the dictionaries are stored in is not readable portable between x32 and x64.
I fixed the problem by building and installing the package from source. I just logged the bug in case someone else gets this problem.