This has a list of what is currently available (in a lot of regions) and some observations as to how it all works. In a nutshell, if any of your devices have an eligible upgrade available (based on the carrier branding, the applications version, the platform version, and the package version), then it will show up. If you do not, then it won't.
OTASL - Official BES Provisioned Versions - Port3101.org : Your BES Connection