When was the last really transformational idea in programming languages?
nostrademons: Most really fundamental ideas are only recognizable in hindsight, after people have built other ideas on top of them.  If I remember the early/mid 80s correctly, the hot language was BASIC because it came with most microcomputers and would supposedly enable a new generation of hobbyist programmers.  (Which it did, but they grew up to program in C++, Python, and JavaScript, not Basic.)There're a lot of really interesting ideas going on in the programming language research community right now.  Subtext, Epigram, associated types, Goo(ze) (which unfortunately seems to have been abandoned), JoCaml, STM, etc.  Unfortunately, it probably won't be possible to judge the worth of these ideas for another 20 years.