Wagtail 1.7: Elasticsearch 2, Smaller Images, CloudFront
1.7 brings a few new features and a lot of polish
Elasticsearch 2
Wagtail 0.1 came with a solid search experience, both in the admin UI and, if you need it, in the front end. We have a fall-back database backend if you don't want the hassle of a third party search service, but most of the time we recommend the default Elasticsearch backend. Since Wagtail was launched there's been an explosion of hosted Elasticsearch providers, including Amazon, Bonsai, and Elastic.co, all of whom provide the full Elasticsearch feature set via a single URL which you plug into your Wagtail settings. Wagtail 1.7 brings support for Elasticsearch 2, the default version for most of these providers. Note Elasticsearch has just jumped, confusingly, to version 5; on first glance it looks like the 2 to 5 upgrade will be much simpler than 1 to 2.
Smaller images
Wagtail has always had a global setting for JPEG quality, but in some cases you may want to specify more compression (e.g. for full-screen background images) or higher quality (e.g. for team member headshots). You can now specify JPEG quality on a per-image basis, using the jpegquality filter. Another new feature is the ability to change the output image format, which might be useful if you want to specify the JPEG compression of a resized PNG upload, for example. Finally, all JPEGs are now run through Pillow's image optimisation methods, resulting in lower file sizes without quality loss for most of your images.
Amazon CloudFront support
Rob Moorman's contribution adds to the list of CDNs / front-end caches supported by Wagtail: now Varnish, Squid, Cloudflare and CloudFront. If you use any of these tools to speed up page serving on your site, you can tell Wagtail to purge their caches when content is updated; if you use another one just fork wagtailfrontendcache.backends and send us your PR. See the Frontend cache docs for more details.
Everything else
Unpublish subpages along with their parents, limit access to form submissions, annotate search results with scores, access more hooks from the page editing lifecycle... our strict release cycle brings a clutch of features to make developers' lives better every two months. Eagle-eyed users may also spot the subtle UI improvements: improved legibility of the admin menu and buttons, along with a redesigned account settings / logout area in the sidebar. As usual, the upgrade considerations are listed in the release notes. For most users, the move from 1.6 to 1.7 should take no more than a few minutes.