html5 localStorage is supported in all modern browsers, as well as in Internet Explorer. Thus, it's usage migth spread quite quickly.Currently a JS function which includes localStorage calls fails.
I have this simple function http://pastie.org/985292
When called in htmlunit (thru cucumber-capybara-culerity-celerity) the error I get is http://pastie.org/985289
I guess also other html5 features, especially those supported by all browsers, will get widespread soon. Nice overview here http://html5demos.com/
p.s. thanks to all developers for running this project
Thanks for reporting, committed in SVN, to be followed by 'globalStorage' and 'sessionStorage' soon