I decided to stretch my brain this semester by doing all the programming and scratchwork for the course I'm taking
My main disappointments in Ruby so far have been the lack of autovivification in multi-dimensional arrays (doing dynamic programming without it is a PITA) and the available documentation not meeting my expectations.
I've subscribed to the "Ruby" tag in del.icio.us, but the S/N is swamped by Rails hype. Ruby does make me appreciate the "Huffman coding" of Perl. Haven't bothered with threads so far as they're not necessary to the problem domain.