@tomascw You can almost just drop postActiv on top of a GNU social instance and not really notice except it will probably be faster.
Some things to do though:
1] Some plugins that are non optional were moved to /modules/ - make sure they're not duplicated or you'll get weird errors from PHP getting confused about the duplicate classes.
2] You'll probably want to use the LogFilter plugin to restrict LOG_DEBUG level stuff, it is very copious information wise now. If you don't, make sure syslog (by default) or your log file (if you set a seperate one) is on logrotate.d
3] Make sure to run /scripts/upgrade.php after you do, it will verify the integrity of the database.
And as always, make back ups just in case something goes sideways.