TomTom's new "Map Update Service", due out later this month, will deliver updated maps to subscribers on a quarterly basis. Subscriptions will cost about $55 per year per country of mapping data for the entry-level TomTom ONE and ONE XL models. Pricing is expected to be slightly higher for the more expensive GO models (the GO models include more mapping detail, such as IQ Routes, speed limit information, etc.).

A subscription-based update model allows customers to receive updated maps more frequently than annual software update purchases, and positions TomTom more as an online subscription service than a retail hardware company. Profit margins on GPS hardware have declined sharply over the past year, and TomTom is wisely predicting that there's more money to be made in software than hardware.

Given the recent pricing trends in GPS navigation, TomTom's subscription service isn't much cheaper than buying a new device every 2 years, so it will be interesting to see if consumers respond to the new subscription model.

TomTom's website says the Map Update Service isn't yet available in North America. No official word yet on subscription pricing for the GO models, or when it will be available here in the US.