The current stable release of Graylog2 is v0.11. (Older releases can be downloaded from GitHub)
AMQP gateway for Graylog2. Introduction blog post and link to documentation: Introducing graylog2-radio
Find the official installation guides on the help pages:
There are several installation resources provided by users. These are not supported or maintained by us.
Find a Chef cookbook here. There also is a Linode Stackscript that will install a ready to use Graylog2 environment: http://www.linode.com/stackscripts/view/?StackScriptID=1970 - You can build up other auto-install solutions on top of the referenced bootstrap script.
Flavio Castelli is maintaining a
SuseGallery image that you can download as ISO or a ready to use
There also is Partylog2 - A ready to install/test Graylog2 appliance available as ISO.
Bapabooie on GitHub built an Gentoo Ebuild: http://github.com/Bapabooiee/bapa_overlay/tree/master/app-admin/graylog2/