A listing on Amazon now shows off the pair of Samba de Amigo maracas from Sega, although they look a little different from what we may have expected:
Priced at $14.99, both the Wiimote and Nunchuk can slot into them. So these are the official ones, but there will also be efforts from third parties - such as this pair from GAME:
Samba time is now less than a month away, the game comes out on September 19th.
CESA-2008:0288 Critical CentOS 4 x86_64 samba Update
Sonic cameo appearance