Google has made Google Checkout free for all 2007.
Boy, they're pushing this one hard.
Reports are the product is getting more solid. You see fewer "I had a bad experience with Checkout" posts bouncing across the blogosphere recently.
And here's the announcement about making it free for all:
How is this promotion different from the free transaction processing I already receive?
Normally, you can earn free transaction processing based on your AdWords advertising spend. If you exceed your free processing for a particular month, you'll be charged a minimal fee per transaction.
During this promotion, however, all of your orders are eligible for free processing regardless of your AdWords spend. You don't even need to be an AdWords advertiser to qualify.
Buying share this aggressively has to be generating attention at PayPal and the credit card processors.
While merchant adoption to date has been somewhat tepid and largely driven by incentives, at some point the sheer weight of money Google is pushing onto this product will make Checkout cross the tipping point, network effects will kick in, and the bulk of merchants will choose to support it to stay in the game.