It’s probably gonna be a big deal.
Previous to this, jQuery 1.x was the IE8-compatible version and 2.x was the forward-looking version which only worked in IE9 and modern browsers. This was confusing to a lot of newcomers who just assumed that 2.x was the latest and greatest version, so now we have”jQuery Compat” 3.x and jQuery 3.x instead.
Please note that there are some breaking changes, plus this is an alpha release, so don’t do anything reckless like using it in production untested.
This article is relevant to my interests. I’ve spent the last couple of months learning my way around Drupal 7 and the Panopoly distro (and waiting patiently for Drupal 8 to be ready to use), and it seems like every time I think I’ve finally got the hang of it, I find something new to try out.