It was Panda 2.3 that caused Daniweb to recover.
All my sites came back completely, and lots more 2X pre-panda traffic levels - all on the 22nd/23rd.
I did nothing to any of them - and I felt they should not have been caught as it was all unique content, high user engagement, great looking site etc. But they were large sites, and those seems to struggle being "classified" by the Panda algo - they said they had work to do on the sites that fall inbetween obvious high quality or low quality.
I think Panda 2.3 introduces some new signals to better classify sites - and my sites (and daniweb) have merely been put into the high quality side this time.