We recently released our iPhone App in May 2013.
Please download it here: Nimble - iTunes Store
You may access Nimble from Safari on your iPhone or iPad as well. We do not have a release date for an iPad application at this point in time.
We do not currently support access to Nimble from Android tablets or mobiles and we do not have a release date at this time.
Please vote for an Android app on our Feature Request forum here: Nimble Feature Requests - Android Application