If you have a 2008 or 2009 S/CL-Class or a 2009 SL/SLK/E/CLS/M/R/GL-Class with a Command head unit your software update should be available mid-October.
If you have a 2008 E/CLS/SLK-Class with a Command head unit the software update is currently being tested and they are hoping to have it available by the beginning of November.
All other 2008 and 2009 vehicles should receive “The Best of XM” without a software update.