in dev, how can I make assets/javascripts changes show up in browser (rails 3.2/chrome 21)

Is this while you are developing on localhost? Do you have the assets pipeline configured correctly in your development.rb environment file? It should be set to auto-recompile on each request. If Chrome is showing you this issue, try using Safari or Firefox and see if the problem travels -- it could be Rails, but it could just be your browser. See if there's a hidden Chrome option to disable cacheing for certain domains or globally. I have Firefox set to use zero disk and memory cache. Yes, it's slower for everything, but I don't have to hold down the Shift key and press Reload to force-refresh while making tiny changes to scripts either, and I don't use Firefox for daily Web driving anyway.