It looks like the Internet's hunch was correct, Yacht Club's Shovel Knight will be getting an official Amiibo from Nintendo, marking the first indie game to do so.
The reveal trailer featuring the Game Grumps appeared today on Youtube, showing off the new features you'll be able to access by using the Amiibo. On both Wii U and 3DS versions of Shovel Knight, the Amiibo will unlock customisation options and new abilities for your knight.
Exclusively on Wii U, the Amiibo will reveal a brand new co-op mode to play with friends while using it on the 3DS version will unlock exclusive challenge stages. Compatibility for other titles has not yet been announced but it wouldn't seem unreasonable for Shovel Knight to appear in Super Mario Maker.