Thanks for your reply! I am running the latest beta, and whenever I open up an .ovpn file by double-clicking, a dialog box says "Tunnelblick is an application downloaded from the internet, are you sure you want to open it?". I click yes, and nothing happens. However, when I quit Tunnelblick, and then drag the .ovpn file onto Tunnelblick in /Applications, it works! I already reset the Launch Services Database, but it still doesn't work.
I had just installed the beta yesterday. I removed the latest Stable using the uninstaller, and then installed the beta. The double-clicking worked on the latest Stable before I used the uninstaller, but then when I reinstalled the beta and stable, neither of them worked in regards to the double-clicking.