The new 0.9 elements are here.
You get them with bower this way:
bower install polymerelements/iron-ajax
I don't think there's an entire element collection ready yet, you should probably download every single needed element.
You can find more info about the new elements in the 0.9 release info:
Where did the elements go?
Not all elements have been ported to the
current release, but we’re porting them as fast as we can. You can
find work-in-progress versions of many elements in the PolymerElements
GitHub organization.
The elements are being reorganized into more consistent product lines,
including:
Iron elements. Basic elements that don’t express a visual style. Most
of the old core- elements are being renamed to iron-. Some former
core- elements that implemented material design (such as core-toolbar,
core-menu, core-header-panel) are being migrated to paper-.
Paper elements. Material design elements. All of the old paper-
elements, plus a few of the old core- elements.
Neon elements. Animation elements.
These element sets will be launching with their own site sometime
around the Polymer 1.0 timeframe. The new site will include API docs
for the elements. If you want to get started with the work-in-progress
versions, the individual repos are the best source for information
about the elements right now.
You can also check out the community Road to Polymer project which is
tracking the status of Polymer elements.
Also, you may find some valualble info in the Polymer Blog. Stay tuned!