Topic: One or two apps?

I have a site which has two distinct functions: forum and inventory listing.  They could share a CSS though it's not necessary but must share a users table so that only one registration/login is required.

Would I be better off writing two distinct apps that share a single database or lumping all of it together in one app?

Thanks in advance for your thoughts on this.

Re: One or two apps?

The advantages of one app:
- singular logins and sessions
- migrations don't clobber each other
- guarantee of using the same versions of all libraries

Personally I'd recommend using the new and improved Engines plugin that allows you to make plugins that function nearly like apps.  If your forum is simple enough then you can put it all into one or two controllers under a single plugin.