There is no confirmation of a 26th release date except from a no-name site. It is a big update, speculation is rampant. Believing something that isn't announced by Microsoft or Major Nelson will set yourself up for disappointment. It could or could not be true, but don't count on it.
Its just usually the confusion between two parts of a company. They may make a release date but don't want to announce it to the public so even if you are correct they may deny it. I can only guess that whoever runs the twitter page didn't know about Nexus.
Here is the latest nexus episode: http://epix.xbox.com/shaXam/0201/db/07/db078664-c87b-459f-bd3f-5a5d03186e61.WMV?v=3#IX-NExUS+Ep4.WMV Skip it to 2:55 to see the announcement. And yes, it is Microsoft!
I installed 12606 by just using the system update downloaded from jessenic's post. After that i connected to live and packet sniffed it downloading the avatars, I don't see it downloading any additional files so im not exactly sure how we can get the avatars working when installing offline. Its likely something else must be re named, i'm not sure what though.
See the file " system.manifest " , there a string Xna_Titlelauncher , that string is connected with the file Xna_Titlelauncher.xex , if that file isn't found the avatars can't be installed
Indeed, i've tried adding Xna_Titlelauncher.xex from an earlier dashboard beta, however that doesn't work. That is likely the problem, however as we have to rename some files too we could be overlooking something such as c49408b9f1639f2866e18e4dcdb31d0538628c08.xcp