Rails - Jun 2006 - Directory/file permissions for Rails app on Apache 1.3.x and fastcgi on Linux

Hello, folks!

I was wondering what the recommended permissions are for the  
following directories/files in a Rails app:

/log (755 seems to work)
/log/fastcgi.crash.log (666 seems to work)
/log/production.log (666 seems to work)

/tmp (707 seems to work)
/tmp/sessions (707 seems to work)

More specifically, why does the executable bit for all users need to  
be set for the /tmp/sessions directory? I tried running it with 706  
permissions. The log claims, "Permission denied." I don''t  
understand-- 706 has writeable permissions for all users.

Also, why does production.log need to exist when starting up?  
Shouldn''t Rails be able to create a file if none exists?

Thanks,

-Anthony