i would call gmail significant but not particularly complex. and anyway, geez, that's google. who else has google's engineering resources?
the trend for years, at least server side, has been towards more dev productivity (eg, coldfusion), not less. i don't get the rush backwards.
one, i think important, point i forgot to mention is the apple/canvas tag HTML5 boogeyman. flex will soon be opensource (except for the tooling & player--which i think adobe simply can't OS because they license stuff in the player). we could soon be faced with a different proprietary overlord, but instead of a fairly open adobe we get apple, who's ideas of technology seem to be more penal colony than their "1984" commercial suggested way back when.