KnowRoaming is now open to the general public.
Reduce Roaming Fees with KnowRoaming
Canadian startup to offer technology aimed at cutting roaming rates
KnowRoaming sticker SIMs can now help more people avoid roaming charges
From what I can tell it's $30 for the SIM sticker and then fixed costs for voice calls, SMS, data, etc. It seems like a reasonable option for people who stay in a country for short periods that don't justify the cost and hassle of getting a local SIM card. The convenience of not needing to swap SIMs is a great feature. Also "Balance Expires after 15 months of no activity."