Just because it's on a different subnet doesn't mean you can't see anything on your home network. Simply add a static route to your home network's subnet, and you will be able to get to it.
It would be nice to come up with some way to apply the route only when using the VPN. Something like MarcoPolo would be helpful. MarcoPolo permits you to run scripts when your "context" changes. For example, when you network connection changes.
Apple may have provided something more straightforward, but I dunno since I haven't played with VPNs on my Macbook, iPhone, or iPad.
Normally, though, VPN client software provides some inbuilt way to do this.