The following extensions have been updated in a major way: flux, fluidcontent and fluidpages. Also updated are vhs, view, fluidcontent_bootstrap, fluidpages_bootstrap (and fed, for supporting legacy sites wanting to try parallel installs).
Today, new major versions of flux, fluidcontent and fluidpages have been released. Although I won't go into all details about the new features (there's a whole lot to cover), the biggest improvements have to do with controller and extension affinity, meaning how well your content relates to a particular controller and action - which means that there's increased support for reading extension keys and controller actions, for example, from the ControllerContext. There's been quite a bit of consolidation going on in Flux, compacting what was once many classes into a lesser number of classes with the same support. Some legacy code has been updated, semi-duplicates removed and as much as possible, repetitive tasks have been moved into new FluxService API methods (which you of course can use in your own controllers).
Naturally EXT:fluidpages and EXT:fluidcontent have been updated to use and depend on this new improved affinity and have received the same care as flux - apart from this, there are no major additions in either of these extensions.
Note: there are upgrade scripts for these extensions; remember to execute them. They cannot do harm but will fix issues you may experience with content relations lost, missing variables or similar.
You have most likely also read about the new extension, EXT:fluidbackend - it, as well as many other new integrations which are yet uinvented, was made possible by the recent improvements made to EXT:flux.
And EXT:flux itself is more solid and faster than it has ever been before. It carefully caches L1 - and has a new debugging core which reports and errors in your templates in a friendlier (and severity-indicated) way using FlashMessages. You can even set a production-style reporting which only reports errors which hinder operation. Naturally both EXT:fluidcontent and EXT:fluidpages use this new debugging core.
The two provider extensions fluidcontent_bootstrap and fluidpages_bootstrap have also been updated to better reflect the current "state of the art" in the new major versions of flux etc.
They've also both received a lot of care in things like adding LLL labels for all texts, improving error tolerance, better reporting of setup-related problems and so on. Note that there is also an upgrade script for fluidpages_bootstrap and that this script makes serious and irreversible changes to your "pages" table and selected page templates, if these use fluidpages_bootstrap. Otherwise they are left completely intact. As always, keep a backup - but as a rule of thumb the update script can be trusted to do its work correctly (perhaps needing a small bit of manual care afterwards).
Then there are EXT:vhs and EXT:view which have also been upgraded, though not to new major versions. VHS is now at version 1.7.0 and has greatly improved handling of secondary CSS assets such as background images and @import statements defined in CSS. Such files are now copied along with the merged CSS and paths adjusted to match, making it easy to control things like cache headers or CDN distribution of CSS assets along with any files referenced by those assets.
Lastly, EXT:fed has been updated to respect the consolidated Services of EXT:flux; this extension's latest release should only be considered a necessary compatibility update for an otherwise obsolete (but still: fully functional!) extension.
Since there's so much to be covered in the three "inner" extensions and the features added here, and since documentation is still incomplete (even more so with the recently added features), I will be covering many of them in the blog here on fedext.net where I will of course be using small examples to illustrate. Stay tuned there to learn how you can kick more ass than ever using TYPO3 :)