Both the Shadowbolt+Cockatrice combo and Shining Armor are now officially in stock on Amazon. Guardians of Harmony looks to be releasing periodically throughout the month over there based on the Amazon listings, so expect more as the days track on. The next wave looks like it's lined up for the 10th, though they have been relatively random so far based on demand.
As always, grab these quick as the GoH figures tend to poof fast. Have some links:
Guardians of Harmony Shining Armor
Guardians of Harmony Shadowbolt and Cockatrice
Thanks to Takutanuva for the heads up!