The latest release notes for the Cloud, pod firmware, Frontline and Portal can be found here.
The Plume Cloud is usually every three weeks.
Firmware releases are not as regular as cloud updates. Although once a new firmware is considered to be a candidate for release, there is a specific timeline followed before releasing to partner deployments.
Can we upgrade the firmware for a specific group of customers?
The is no option currently to push a firmware update to a specific of customers. Firmware can be updated manually for individual networks using Frontline.