Cached/offline maps for iPhone?

I'd like to use use maps in my application, so that there will be as less as possible traffic. Perfect solution woul开发者_Python百科d be caching of map slices. I know it's not possible with google maps (license). I took a look on OpenStreetMaps and it seems as good solution. The next: SDK. The only one I've found is from CloudMade. The problem is, I found no related API methods for caching/offline calls. Are there any alternative solutions?

You might find more information on the Route-Me project Wiki.