Donovan has already done a TON to raise the awareness of Everton over here. He is FAR more recognizable than Howard (as a celebrity, not a footballer, but that's what most american's care about).
While I think 90% of the move was simply Moyes seeing a need and finding a clever way to fill it with a solid player, the additional 10% of increased exposure over here will only do Everton good.
For those of you thinking ESPN doesn't really care, just wait. They bought up Setanta's contract and are now showing EPL games (in HD). This is the run up to the world cup. EPSN is going to do EVERYTHING in it's power to play up soccer and Donovan and even the EPL over the remainder of the season... it is in their own best interest. Donovan's first Goal in blue will be all over sportcenter. Had Everton won the arsenal game, the headline would have been about LD.
As long as donovan gets solid play (Arsenal game was a GREAT start) this will only be good for Everton's exposure over here. While we may not buy a ton of shirts at the moment, it takes time for people to jump on a bandwagon. Everton need to finish in the top half again though. American's don't want to support a below average club.