TeX Live is included in a number of system distributions (“distros”). TL was originally conceived and is still distributed as a benefit of the TeX user groups, including prebuilt binaries and independent of any specific operating or packaging system, but we are glad to see it being used as the basis of the TeX installation of many systems.
We have a mailing list specifically for discussion of TL integration in distros: tldistro@tug.org. Feel free to join or peruse the archives if you are interested.
System distributions have their own packaging systems, so tlmgr is not used for TeX package updates. The fmtutil and updmap programs are typically used directly, and hyphenation patterns (maintained via tlmgr generate language in native TL) are handled differently by each distro.
If you are considering (re)packaging TeX Live, then carefully consider each of the above items, as how you handle them plays a large part in whether TeX successfully works for your users. Purely as an example of one distro handles this, you may wish to peruse the TeX-on-Debian and Debian-TeX-Policy documents. (Again, we are not evangelizing for Debian or Debian's decisions, just noting that they have written up many of the decisions that anyone creating a TeX distribution needs to address.)
Here is a list of distros and their respective maintainers, to the best of our knowledge.
Please send corrections to tldistro@tug.org.
Again, please send additions to tldistro@tug.org.