The phone itself has the harware capability; much like the design of the Samsung Instinct. Although currently there are no built in features for a "flash" notification. Hopefully an update will correct the issue in the future.
What I don't understand is why, if this was a problem on the Instinct and an update was later released, why wasn't it included on the Moment for messages and notifications? What makes it really weird is that, at least on my Moment, when I get a call, the home, menu, and back buttons light up, but unfortunatly not for messages and notifications
Ok this is what I did to get a reminder of missed calls, text messages, and unread emails. There are 2 app's called Missed Call (free), & Lock 2.0 (1.99) on the Android market. The Missed Call app only seems to work when both apps are running, and the toast pop up is turned on in the Missed Call app settings (different settings for text, calls, and mail). So after the first notice that I have mail, text or a call (I have M.C. set for 3 min reminders) every 3 mins the screen lights up and phone vibrates. Don't worry about the color for LED setting as the Moment has no LED's. This may be something you want to try, if it doesn't work all you have to do is uninstall the apps. No big woop. Good luck
Flash Notify on market is working for me on my moment on 14 and also worked on 05. The whole screen blinks and the button backlights blink. You can change setting, timed blinks, end blinking, etc. The developer is working on dropping the screen flash and just flashing the button lights. Notifies of missed calls, texts, and maybe emails--have to check. You do have to go to the actual notification to end flash--maybe atk does it too. Restarts on its own after being killed with atk. Doesn't seem to chew up too much battery but I'm pretty battery conscious. Free on market and has two donate sites on market as well to sweeten the deal for his work. Just an fyi that this is working on my moment after updating to 14 by computer (not at repair site). My phone is not rooted. Be well.