EA has registered Plants vs Zombies Adventure” under multiple domains.
Superannuation spotted the registrations, which were all made by the publisher earlier this month. The term likely has nothing to do with Popcap's upcoming sequel to its hit casual game, as its to bear the name Plants vs Zombies: Garden Warfare; but may relate to the Team Fortress 2-style game set in PvZ's universe the studio was rumoured to be working on back in December.
VG247 also points out Popcap has recently released a series of franchise spin-offs on Facebook, so the title very well could be a social game – or something entirely new.
Or EA could just be beating squatters to the punch. There's nothing to go off but those uninformative domains for now.