How to upgrade to GNOME 3.30 on Ubuntu 18.04.1
Solution 1:
According to The Best New Features in GNOME 3.30 :
It will be available to download as source code from the GNOME Gitlab page, and be available to try via a live USB image.
Although many Linux distributions come with GNOME by default few distribute major new releases right away, instead choosing to ship the update as part of a new release.
Rolling release distros are the exception of course, so Arch, Manjaro and others will likely make this update available soon.
Please note the second paragraph.
There's also a detailed answer to an earlier question of similar nature here: How to get Gnome 3.14 on ubuntu 14.04.
Edit: and now GNOME 3.30 is available via Flatpak.
Edit on 20181121: I couldn't find it in https://flathub.org/apps/category/All