Looking to reinforce it's pitching staff after Takashi Saito and Hiroki Kuroda opted not to participate, Japan has added MLB relievers Hideki Okajima and Masa Kobayashi to it's provisional WBC roster. Lotte infielder Tsuyoshi Nishioka and one of my favorites Hayato Terahara were among the other notables added in the most recently announced roster.
And of course, the WBC will afford international fans the opportunity to see Yu Darvish and Norichika Aoki live against top level competition. Mainichi has the complete provisional roster published in Japanese, but I haven't found the latest version in English. I'll translate Mainichi's later tonight if an English version hasn't shown up by then.
NPB players also appear on provisional rosters for Australia, Canada, Korea, Taiwan, Venezuela, and Panama.