Currently, OpenGoo has a unique URL for files. The format is:
http://<opengoo_root_url>/index.php?c=files&a=file_details&id=<file_id>
It isn't easy (or even possible) to figure out what the id of a file is, but if you happen to know it...
We are working on OpenGoo's navigability, and among the things we want to implement is that the browser's address bar reflects where you are inside OpenGoo, like in Gmail, that when you go to the inbox it appends #inbox to the URL, and when you open an email it appends a slash and the email's id. Having this would allow the user to copy the URL from the address bar and share it, bookmark it, etc, and would also allow to navigate OpenGoo with the browser's back and forward buttons.