We haven't patched content or balance because we are trying to have a stable launch window, with as few variables as possible.
With that said, new content is coming at the end of June -- Competitive Play mode. We should also have a minor balance patch (hopefully) this week.
As those who were in the beta can attest to, we patched quite frequently and liberally during beta. Now that the game is live, we want to be careful to not overly disrupt the game balance too frequently.
In general, you can expect content patches, balance patches and minor bug fix patches to happen regularly now that we're clearing the launch window. But don't expect balance to change each week... we don't feel like that would be healthy for the game.