After a long day of travelling to California on Sunday I noticed in my twitter feed a number Japanese-language tweets talking about Cumulus, an Android app for managing VM instances within CloudStack. This app interacts directly with the CloudStack API. Merely input your CloudStack URL with a username and password and it will automagically acquire your API and Secret keys. Once you've connected to your CloudStack instance you're provided with detailed information and status of your virtual machines and snapshots, as well as being able take actions (start/stop/reboot a VM and deletion of snapshots)
I particularly envision some of our service provider users hardcoding a URL and changing the branding so they can have a branded Android App for their customers. The app is licensed under the Apache 2.0 license, so forking and customizing should be pretty hassle-free.