Javier "The Latin Love Machine" Valentin is playing in the Carribean Series this weekend for the Carolina Giants of Puerto Rico, who are hosting the round-robin tournament. According to Derek Jacques at Baseball Prospectus, Valentin has been pushed into infield duty by the catching tandem of Jose and Yadier Molina. I imagine that means he's playing first, though I guess he could be at third base as well (edit: jhelfgott [see below] has Ray Navarrete playing third for the Gigantes, so that would mean that Javy's the first baseman). I'll see if I can find some boxscores as the week progresses.
Edit: ESPN.com does have a scoreboard on its website for the series. Hopefully that will include box scores and writeups as well. The first game started 24 minutes ago, though no updates yet.
Edit2: One more thing. jhelfgott has a preview of the series, and hopefully some running commentary, on his blog, Global Baseball. He's been working on an upcoming book about international baseball since last summer and has used his blog (intermittently) to chronicle his work.
Edit3: Sorry about all the edits.