Sgt_Kickaxe - 12:00 pm on Sep 20, 2012 (gmt 0)
It might actually help them identify spammers.
If there is one thing I know about Google it's that they trust NOTHING a webmaster adds to a page in terms of allowing it to help in serps. They do however enjoy using signals to gather data and/or demote sites algorithmically with.
Google killed the keyword meta for a reason, did they bring this one back to help ensure that pages with this tag remain in serps for only xx number of days? Time will tell.