As per the Reddit leak earlier this week, Wonderlands is set to be a Borderlands spin-off featuring Tiny Tina:
Wonderlands: Codename Daffodil – It’s a Borderlands spin-off title featuring Tiny Tina. The final name could also be “Tiny Tina’s Wonderlands” (as this is the name that Gearbox already trademarked.) Seems to be the same style as all other Borderlands games with “Multiclass-Heroes” to play as. This spin-off is rumoured since last year, so I guess this isn’t really new. Reveal should be expected at E3. EDIT: Here’s the trademark for Wonderlands
Square Enix’s E3 press conference is set to take place on Monday morning. You can find all of the E3 press conferences in Aussie times HERE.