arch in bottle's filename

[sevan]

Just to keep notes, I've been playing with generating bottles and noticed on my iBook running Leopard that it had generated the bottle with the arch already in the filename, automatically.
Digging a little further I noticed in Library/Homebrew/bottles.rb that the logic seems to originate from there, though there are further issues.
Build on a G5 host with --bottle-arch=g3 results in the filename ending with .tiger_g5.bottle.tar.gz