The current stable release line is 1.6. For more information about older versions, see the FAQ item about supported releases. Versions 1.2 and older should no longer be used due to known security issues that cannot be resolved in that code base.
Official release distribution
You can verify the release with the command
$ gpg --verify ledgersmb-<version>.tar.gz.asc ledgersmb-<version>.tar.gz
There are production level Docker images available on the Docker hub. New containers are released on every stable (1.5) release. Newer release have acceptable sizes (~ 175MB) and in the 1.6 images, printing problems have been resolved as well.
The docker repository identifier is "ledgersmb/ledgersmb" with the "latest" tag always pointing to the most recent stable release, which is currently the most recent 1.6.x release. The "master" tag points to the most recent alpha or beta of the development version (1.7).
A Debian package is not available in Debian Stretch (stable) due to problems with the Dojo dependency (which fails to build). Packages are available for jessie (oldstable), jessie-backports, wheezy (oldoldstable), wheezy-backports, and the current Debian Unstable (Sid).
Newer packages than those distributed by Debian can be found in the LedgerSMB APT repository (along with their updated dependancies as necessary).
Ubuntu packages are available in the standard distributions as of Trusty (14.04 LTS), Xenial (16.04 LTS), Yakkety (16.10), Zesty (17.04) as well as the current development release (Artful) .
Newer packages than those distributed in Ubuntu can be found in the LedgerSMB PPA repository for Trusty (14.04 LTS) and Xenial (16.04 LTS) and others as necessary or requested (along with their updated dependancies as necessary).
RPM Packaging contributions solicited.
FreeBSD Packaging contributions solicited
OpenBSD Packaging contributions solicited.
Virtual Box No up-to-date images at this time.
Keeping up with the latest developments
The latest 1.5.x, 1.6.x and 1.7.x are available directly from GitHub as a .zip file (it's not an official release, but has the latest fixes you may need) 1.5.x from GitHub, 1.6.x from GitHub, 1.7.x from GitHub Check the repository for the change log in 1.6.x from GitHub or the changes in bleeding edge ('master').