This plugin is a reasonably non-dirty workaround to the existing issues with browserid and PhoneGap.
It includes code from the Couchbase fork of the Mozilla iOS Persona SDK.
The gist is that rather than trying to work with the PhoneGap web view, or the ChildBrowser plugin, or the system browser, instead it just brute forces a new webview, just like you would do if you were a native app.
To install, use plugman and run it like this:
plugman --debug --platform ios --project $MYPRJOJECT --plugin git://github.com/couchbaselabs/cordova-browserid.git
Sorry, only iOS support for now. Happy to accept pull reqs for Android.