[I am traveling today, so it might be a one-off due to low band-width at the hotel, but in case it helps others]
I was installing Live writer and got a prompt to install the .NET Framework 3.5, I agreed to do that and got a “following feature could not be installed. Error: 0x800F0906.
Fortunately, I still had the ISO from when I installed consumer preview , so I used the local sources.
If you see the error above, try this from an elevated command prompt.
dism.exe /online /enable-feature /featurename:NetFX3 /Source:h:\sources\sxs
where “h” is the drive where you have your win8 installation files (or where the iso is mounted, replace the path appropriately ).
Happy Windows 8 coding!