Sharding MongoDB internationally with data stored based on location
Solution 1:
Some of this already in place with MongoDB, see a decent write up here:
http://www.mongodb.org/display/DOCS/Data+Center+Awareness
In terms of read-routing, there are some implementations in the drivers, but it is not built in. The feature complete version of localized data reads is intended to be released with 2.2
If you would like to take a look at the two most closely related core server issues, you can take a look here:
https://jira.mongodb.org/browse/SERVER-3062 https://jira.mongodb.org/browse/SERVER-3358
And, of course, you can then vote on the feature to bump it up the list :)