On Feb 4, 6:07   
> [Note:         
>
> On Thu, Feb 4, 2010 at 5:44 AM, Luis Lavena <luislav... / gmail.com> wrote:
> > When are you getting this?
>
> Installing the mysql gem, under Snow Leopard unless ARCHFLAGS=-arch x86_64
> is set.
>

The offending code is here:

http://github.com/luislavena/mysql-gem/blob/master/ext/mysql_api/extconf.rb#L1-8

Since I haven't upgraded my Leopard installation to Slow Leopard, I
cannot test all these details.

I've that *cough* feature *cough* from DataObjects, which got removed
after SL release.

Since I don't have a spare Mac for work, couldn't afford the time will
take to rebuild my whole environment due the craziness of mixed 64/32
bits applications and libraries.

If you take a look to current DataObjects, maybe you can bring these
changes in:

http://github.com/datamapper/do/blob/master/do_mysql/ext/do_mysql/extconf.rb

--
Luis Lavena