This isn't such a big deal for people me who already run Google Talk or Thunderbird for Gmail notifications but it's pretty cool nonetheless.
Many of us are guilty of constantly switching back to Gmail to check for new messages. And if you’re like me, you’ve probably missed an important chat message because you weren’t looking at your Gmail window when it came in. If you use Google Chrome, these days can be over since we just launched HTML5 desktop notifications which display pop-ups whenever a chat message or new email arrives.
For some reason this isn't working for me. I sent myself a couple of test emails. They showed in my inbox but the notice didn't pop up. Both with Chrome maximized and minimized. Strange.
Edit:
Scratch that I had to give approval to Gmail in Chrome. Funny I didn't see the notice with the first couple of test messages though.
I'll check it out. I've had the same problem where I get a Gmail Chat but I'm not in front of the compute and don't notice it until the next time I check my email. It's worth noting that when you get a chat and you use Firefox I am notified by the text change in the system bar between the start button and system tray on my desktop.