We're doing an AMA over at Reddit as well: http://www.reddit.com/r/ecommerce/comments/35zpxh/xpost_from...

This looks really interesting. What does this use as the source for product data?

Hey! Semantics3 has always had a solid database of products and pricing information which we keep constantly updated across various retailers. The Push API is just another interface to that database.

what do you mean by "high frequency"?

The products will be checked frequently for price updates, which means a price change will be detected sooner as well.

Generally, propular sites and products will be refreshed much more frequently - as often as every 24 hours