Android :: OAuth Secrets In Mobile Apps

When using the OAuth protocol, you need a secret string obtained from the service you want to delegate to. If you are doing this in a web app, you can simply store the secret in your data base or on the file system, but what is the best way to handle it in a mobile app (or a desktop app for that matter)?

Storing the string in the app is obviously not good, as someone could easily find it and abuse it.

Another approach would be to store it on you server, and have the app fetch it on every run, never storing it on the phone. This is almost as bad, because you have to include the URL in the app. I don't believe using https is any help.

The only workable solution I can come up with is to first obtain the Access Token as normal (preferably using a web view inside the app), and then route all further communication through our server, where a script would append the secret to the request data and communicates with the provider. Then again, I'm a security noob, so I'd really like to hear some knowledgeable peoples' opinions on this. It doesn't seem to me that most apps are going to these lengths to guarantee security (for example, Facebook Connect seems to assume that you put the secret into a string right in your app).

I don't believe the secret is involved in initially requesting the Access Token, so that could be done without involving our own server. Am I correct?