Lyonthri posts in German that Wrath of the Lich King will be available for download next Thursday.
I'm scratching my head here too. This was brought to my attention a short time ago, and has since showed up on MMO-Champion as well. So something is definitely up. We're paying attention to the Customer Service Forums tonight in hope of getting some more clarification from Blizzard.
The full German text of Lyonthri's post, along with a Google translation, appears after the break.
Update 4:40 a.m. EST: Claudiog has clarified his earlier point that he said there should be no expectation of a digital download being available on release day, not that there would not be one.
Updated 3:17 p.m. EST: Lyonthri has since updated his post informing us that he is not saying there will be a digital download available on release. He apparently misspoke.
ein kleines Update an dieser Stelle: Die Downloadversion von Wrath of the Lich King wird am Release-Tag zur Verfügung stehen.
Google translated English version:
A small update at this point: The downloadable version of Wrath of the Lich King will be available on release day.