The VM Storage Policy API (previously known as VM Storage Profiles) is part of the vSphere 5.5 release and is exposed as a separate API endpoint on the vCenter Server. You can find more details in the vSphere Web Services SDK download and there is a spbm directory which contains the API reference docs, Java SDK samples + WSDL (if you wish to build your own language bindings). I will be publishing an article tomorrow with more details on www.virtuallyghetto.com
In terms of vSphere Tagging APIs, they're currently not available in either the vSphere 5.1 or 5.5 release. However, with the vSphere 5.5 release, we will have PowerCLI-only cmdlets for managing vSphere Tags which will allow you to automate the lifecycle of vSphere Tags but will be PowerCLI only for this release.