It'll be an error, since they still had the usual "Just Remember – All Same Day as Print DC Comics go live at 2pm EST on Wednesday, while all others will be live around 10am" in the releases list this week.
Of course, they should just release all new comics at something like midnight EST and be done with it.
Nook version is also already available. DC likely didn't want to give Amazon or anyone else a competitive advantage over Comixology.
I would like to know if the Kindle Version is also available for customers in the UK. It is NOT available via amazon.de, which is tremendously stupid. The Kindle Fire here in germany is nothing more then a "normal" Kindle with color. It absolutly is not for reading comics since the ComiXology app is not available either.