Import, Export and Sync
For both of these, you will need to purchase Web Access.
To export, go to the More tab, tap export and type a name. To import, go to the More tab in the iPhone app and tap Import. You should see a list, so pick an export. Warning: importing will not merge your data! Instead, it will replace it. The Export/Import feature is currently only for backups and safekeeping. In the future, that will change.
Included in Sync is the ability to view your Forecast on the website. For now, you cannot edit this. Also, the forecast is not computed on the server, so it is only updated when the app is run. This, of course, will change in the future.