This is a bit of a surprise, and apparently steams from a cock up on the US webstore, hence being so far ahead of any leak we've seen in a fair while.
The following are pictures of the new High Elves, and, possibly, the Army Book cover.
There's a fair bit to take from the army picture, with the Phoenix kits being the most obvious. However, looking just below them there is alsowhat looks to be a new war machine kit.
It'll be interesting to see if the High Elves get a properly huge monster (or equivalent) kit, or, if, like the Daemons, they'll get a handful of warmachines.
via Fields Of Blood, and many other places.