Is there an upgrade path from 32-bit to 64-bit?

[Gerry Reno <greno verizon net>]

We're finally getting rid of the last of our 32-bit hardware and now we 
would like to migrate all machines over to 64-bit.  I explored this 
migration idea a couple years ago on the mailing lists and basically the 
answer was - don't know.  The few who had tried said that the ended up 
with a running system but that it had some weird quirks every now and 
then.  Has anyone managed to successfully migrate a system from 32-bit 
to 64-bit using either anaconda upgrade or yum upgrade without ending up 
with a lot of quirks?  Is there some recipe for doing this successfully?

Regards,
Gerry