There are some undocumented methods in 2.0rc2 which should provide this information for you. Note that the locations/signatures of these may change by the time another public sdk is released.
//Get the current environment's global context
var context = Rally.environment.getContext();
//Get the current user's permission set
var permissions = context.getPermissions();
The permissions object is an instance of Rally.auth.UserPermissions, which has the following pertinent methods:
... and more.