I first saw it on Twitter as a "trending topic," so I have no idea who to credit for the news, but I've seen it several places from excellent sources. The A's have agreed to a four year, $36 million dollar deal with Cuban defector Yoenis Cespedes.
I'm no prospect maven and I know next to nothing about Cuban baseball, but Baseball Prospectus's Kevin Goldstein rated Cespedes as the 20th best "prospect" in baseball, if you can consider a 26-year old a prospect, which would give the A's 7 guys in his Top 101.
Here's Cespy's Wikipedia page for those who want more information, and more analysis will follow in the coming days. I don't know if he has a nickname already, but I started with Cespy, and I expect significant contributions in the comments.