Version 2.0.13146.0 is currently the latest public version.
You can check your kernel version in "System -> Console Settings -> System Info". The line at the bottom contains your kernel version in the format K:2.0.XXXX.0, where XXXX is your kernel version.
|2.0.1888.0||November 22, 2005||Original shipped version|
|2.0.2241.0||November 22, 2005||Update available at product launch|
|2.0.2255.0||Blocklist for certain .xex file|
|2.0.4532.0||New identifier X with value 2BB7-8E09-0188-D795|
|2.0.4552.0||Fix unsigned code vulnerability|
|2.0.5759.0||Added Instant Messaging|
|2.0.5766.0||Wireless guitars Yet unknown fixes|
|2.0.6683.0||Fall Update. Timing attack works (dependant on CB).|
|2.0.7357.0||November 19, 2008||New dashboard ("NXE")|
|2.0.7363.0||February 3, 2009||HDMI audio fix|
|2.0.7371.0||April 2, 2009||Fixes Xbox Live issues|
|2.0.8495.0||July, 2009||Update preview|
|2.0.8496.0||July 31, 2009||Update preview (second)|
|2.0.8498.0||August 11, 2009||Public Dashboard Released|
|2.0.8507.0||Preparation for newer dash|
|2.0.8955.0||Blocking 3rd party storage devices, adding WPA2 support for wireless adapters|
|2.0.9199.0||USB storage support added|
|2.0.12611.0||GUI upgrade for Kinect release, ESPN on Xbox LIVE released|
|2.0.12625.0||Adds further anti-piracy 2.5 scheme to more popular games Halo: Reach, Call of Duty: Black Ops and Call of Duty: Modern Warfare 2.|
Fixes ‘Boot to Disc’ option.
|2.0.13146.0||Reflashes the DVD drives to support XGD3 Media : PLDS DG-16D4S, PBDS VAD6038 and PLDS DG-16D2S, to a new stock firmware : 0272, 04421C, 02510C. Also patches Samsung MS25 & MS28|
Anti-Piracy 2.5 scheme updated.
Please note: In order to use the SMC Hack, you must not have installed any of the 849x kernel updates.