root@weather:~# /opt/vc/bin/vcgencmd version
Jan 20 2015 18:10:55
Copyright (c) 2012 Broadcom

version b95d88a52e7948aa6036ee43cff39d28fe1a54bd (clean) (release)
root@raspberrypi2:~# rpi-update
*** Raspberry Pi firmware updater by Hexxeh, enhanced by AndrewS and Dom
*** Performing self-update
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 10185 100 10185 0 0 31602 0 --:--:-- --:--:-- --:--:-- 40098
*** Relaunching after update
*** Raspberry Pi firmware updater by Hexxeh, enhanced by AndrewS and Dom
*** We're running for the first time
*** Backing up files (this will take a few minutes)
*** Backing up firmware
*** Backing up modules 3.18.11-v7+
#############################################################
WARNING: This update bumps to rpi-4.0.y linux tree
Be aware there could be compatibility issues with some drivers
Discussion here:
https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=113753
##############################################################
Would you like to proceed? (y/N)

root@raspberrypi2:~# /opt/vc/bin/vcgencmd version
Apr 21 2015 14:42:19
Copyright (c) 2012 Broadcom
version 2d5ad04b63af4233440c3f7c8587108223201102 (clean) (release)

now the weather pi and the pi2 are at
Jun 26 2015 13:37:00
Copyright (c) 2012 Broadcom
version ccd74887d783fb00f92c3126859ec69b8b2f21d5 (clean) (release)