Yes, Covve fully supports iPhone and Android.
The app can operate in two modes:
a) Fully in sync: You can use this mode if you sign up to Covve through the app. This will enable you to synchronize your native iPhone address book with Covve
b) No native sync: You can use this mode if you log in to an existing Covve account through the mobile app. In this mode you can view and edit your Covve data but the changes will not be reflected in your iPhone's native address book.