Well, it certainly looks like there are some violent wack jobs hanging on to the Earth Liberation Front movement - as evidenced by some rather spectacular fires in the SE Snohomish County community of Maltby.
The operative phrase in that sentence is 'looks like'. It is quite possible that this is just an arsonist torching unsold multi-million dollar homes (the one sold was the only one untargeted) using the ELF as scapegoat - and scoring a few political points in the process. These houses are big, that's true, but they were also showcases for environmentally friendly building processes.
The current court case regarding the accused look out for the alleged ELF bombing of the Center for Urban Horticulture, in Seattle is worthy of note. Though this particular individual is claiming innocence I do believe they have confessions, and deals, from the alleged other participants.
FWIW though I don't know the particulars of those other individuals - and targeting a bunch of Master Gardeners just seems plain weird.
Odds are definitely pointing to the ELF. Not a long shot, that. News flash to Hillary, Barack and McCain - it looks like we've got our own 'Al Qaeda' movement brewing in America, no need to import it.