Updated to Sass 3.2.13. Hence the generated CSS looks completely different. Yay. Epic fail.
Finally get rid of the 'jumpy links'! :)
Hide the 'Downloads' section in the sidebar if there are zero files attached to a node.
Make the breadcrumbs less 'screamy': never add the title, and only show them if there are 2 ancestors.

(If there is only one ancestor, then the tabs at the top of the page will already show the hierarchy.)
Make the permalinks better: just show the infinity symbol, not the time and date; show the time and date on hovering the link, and include the timezone there.
Don't show the size of each download (attached file), that's more noise than signal.
Only showing the manual subject for very old node comments didn't work anymore since the last server upgrade to PHP 5.4.
Additions/overrides for drupalstuff.scss: fields whose labels should be displayed inline were not yet being displayed inline.
Some typographic refinements (at least to my eyes): much more whitespace *above* h2/h3, and much less *below* h2/h3. Also: more whitespace above the first paragraph of an article. This results in a much clearer visual hierarchy, easier navigation.
Restructured the 'full node view' page layout: less excessive breathing room on the left side, more breathing room on the right hand side of the node's content. This makes the reading experience significantly better on narrow screen widths.
In response to the restructured 'full node view' page layout: allow the node title and the tags associated with it to go a little bit beyond the strict grid structure (yields a bit more organic result).