Not trying to start another notification-LED debate - the iPhone doesn't have one, probably never will, and that's pretty much that. But if you wish it did, take a look at this thing. I've had one for a week and I'm pretty happy with it. There are a few UI quirks in the app, but once you've got it configured, it's set-and-forget.
If you buy one, order directly from the company and specify that you want one with the new firmware. Existing stock at Amazon, etc. might be the old version.
If you buy one, order directly from the company and specify that you want one with the new firmware. Existing stock at Amazon, etc. might be the old version.