Hi, I would like to know if there is any forum, mailing list or website so I can follow the SME 8 development with more details.
Most of the development discussion with respect to SME takes place in the bug tracker. You can also subscribe to the devinfo mailing list. All of the developers associated with SME subscribe to this list. If you have question about SME development, post it to this list. You will very likely get a response within hours of posting your question
The wiki is not updated, the forum doesn't have a SME 8 section and the mailing lists or are almost dead or there isn't any piece of information about SME 8.
This is a bit of an exaggeration:
1. The wiki has had recent updates with respect to SME 8:
http://wiki.contribs.org/SME_Server_8 was registered in the wiki not even a month ago. I'm certain that there is a beta 3 update in the wiki.
2. The bug tracker is very active with development discussion.
3. The forums don't have a SME 8 section yet because it isn't released.
You need to plug in and actively ASK about SME 8.
I would like a source of information that kept me in touch with the release schedules and recent fixes on the system. Is there such a thing anywhere?
There isn't a release schedule. It will be released when it's finished. I know this isn't the answer you want, but this is the answer you will get when you ask for a release schedule for many of the GPL projects out there. Remember, none of the SME developers are being paid to develop SME so there is no schedule.
You will find a list of "fixes" for SME 8 in the bug tracker.