Site organization (with rails app, and other)

[vellutoblu]

I need for my site a structure like this :

public_html/app1 -> ~/rails/app1/public (www.example.com)
public_html/app2 -> ~/rails/app1/public (app2.example.com)
public_html/site1 (site1.example.com)
public_html/site2 (site2.example.com)

I've only one domain that points to a rails application (app1), now linked directly on public_html.
The problem is that i don't like put other subdomains dirs in the public folder of my rails app.
One solution is to made a rewrite rule in public_html/.htaccess that rewrites all to public_html/app1 (any example?).

There are better solutions?

Thanks!
vellutoblu