all in.
un-media'd sources should match without question
not necessary, as IE8 and under don't have media query support anyhow
reused the existing var
Exit early if picture is natively supported (totally hypothetical at this point). If Modernizr is available, add a test for picture to it (adds handy picture/no-picture classes to HTML element). Also uses Modernizr's mq shim if available. Both these enhancements do NOT REQUIRE Modernizr and take just a few lines to implement.
Removed Modernizr hooks
Merge pull request #3 from gordonbrander/master

Exit early if picture is natively supported.
added noscript to the recommended markup pattern (for fallback only) and generated the child img element if it's not already present. With this tweak in place, the picture markup pattern supports non-js fallbacks, avoids prefetch, and enjoys all benefits of the proposed picture element functionality. Production ready, perhaps.
Merge remote branch 'origin/master'
updated link to demo
Corrected minimum stated width in comment for largest picture
Merge pull request #6 from tnorthcutt/patch-1

Corrected minimum stated width in comment for largest picture
demo link update - gh pages seems to be working now
code style, whitespace, comments.
matchmedia and media query support should not be required for picturefill to run - source elements with no media attributes or media attributes specifying media types (but not queries) do not require media query support. For media attribute support in general (even in non-query supporting browsers), matchMedia polyfill is necessary, but this change ensures a non-media source element will load in JS environments. Fixes #9
comment change
fixed w.document reference
fixed a typo - no !! should be there.
by binding to domready and load events (as a fallback), we can deliver IE 8 and older browsers with fallback content using any source elements that don't rely on media queries (note: media types are fine though). In order for this to work, the script needs to run from HEAD, like any HTML5 shiv would. Script still works in non-IE browsers if it's not in HEAD.
Fixed a couple jshint whitespace warnings