Natively, both Android and iOS is supported with a nearly identical feature set. However, if you do not have an Android or iOS phone, your phone may be supported.
Blackberry
Download for Blackberry
Blackberry is currently in beta. During this time, all Blackberry phones version 8900 or higher are supported, but the Waze client will not have an identical featureset to other phones until this client moves out of Beta.
Windows Mobile
Full Windows Mobile List
Windows Mobile phones are not all supported, but for those that are supported, they sport a nearly identical feature set to the Android and iOS versions. See the list above for more information.
Symbian
Symbian Supported Devices
For devices that have the Symbian OS, some of the Nokia devices are supported. For those that are supported, they have a nearly identical feature set to the Android and iOS versions. The list above can provide if your phone is supported or not.