To concat all the Information in here and fill it up with something official:

Stable LTS Supported until March 2017:
Not semver but artificially semverized to fit into the new versioning
2.06.X a.k.a. 2.6

Stable current (Support until at least 2018 )
Since 2.51.1 under semver MAJOR.MINOR.PATCH
2.5X.X a.k.a. 2.50/2.51

Coming Version (release tba, currently in early alpha)
semver from the beginning MAJOR.MINOR.PATCH
3.X.X

And by support is meant making security-updates and bugfixes for the software.
We only give technical support to customers of the premium packages or our professional hosting service.

I hope this clears things up a bit.

ok now its clear! thanx all for the info.
i'm not looking for unpaid work, just the official release schedule to understand LS way