I asked the Codeforces about recent progress. That's what they told me:
true language autodetection (Polygon tries to compile a source using different dialects),
you can upload multiple items simultaneously on the tabs Files and Solutions,
feature to view stderr for invocations,
Rejudge/Abort links inside invocation page,
In addition, the work on API continues.
preview comment when editing;
filter by problems on hacks page;
improved choice of t-shirt size;
the ability to change the handle once in the first 7 days after a registration;
improved performance of some API methods.