An update (with another one to follow shortly). The Google Earth Community is now live to everyone again. There are a few issues to be aware of.
1) If you had an account in the old GEC, you will need to claim your username and posting history as the first thing you do in the new forum. To do this, visit the GEC and click "Join Group." From here, you will be taken through the process of linking your old GEC account with your Google account. Please note: you have the option of linking your GEC account to your Google profile, but you don't have to. If you do link to your Google profile, folks on the GEC will be able to see your profile from the forum. The takeaway, if you want to remain anonymous, don't link to your Google Profile. If you are having any problems joining the group and claiming GEC nickname, please use this Help Forum thread to report them.
2) Not all redirects to GEC threads are live yet. We tested this before launch, but the redirects seem to be not working correctly and we are trying to get a fix for this ASAP. A bit longer out, links to KML/KMZ content hosted on the GEC will not redirect also right now. Both of these are important for us to get fixed as soon as possible.
3) Currently, the "Share to the Google Earth Community" tool from Google Earth is still not live. We're aware of this and it's also a short-term priority to get fixed and live.