In a story from JoBlo it looks like Lindsay Lohan posted on her Twitter page that she might've just joined the cast of Machete today.
Apparently, the actress slapped up the words:
"something was made official today!"
and then she linked it to the Machete IMDB page.
Currently, some of the other actors rumored to be a part of this Robert Rodriguez/ Ethan Maniquis experiment are Michelle Rodriguez, Steven Seagal, Jonah Hill and Robert De Niro.