Valve appears to be locking threads on the Steam community forums that discuss or mention holiday sales occurring on non-Steam digital distribution platforms like Xbox Live and Amazon, reports Piki Geek. Here's a post from the forum with links to several locked threads, all of which reference other sales.
If true, this is definitely uncharacteristic of Valve, who normally don't stoop to such shady activity. Granted, the forums are theirs to do with as they please, but it seems so unnecessary to block all discussion of their competitors. Maybe something else is going on? Let us know your thoughts in the comments or on Facebook or Twitter.