I missed this news when it happened a week or so ago, but Anthony Rizzo was called up to AA recently, taking starting 1B spot recently vacated by Lars Anderson's promotion to AAA. Rizzo's final line at high A Salem was .248/.333/.479. The average is a bit lower than you'd like to see, although the questions surrounding him coming into this season were about his power potential. Rizzo is off to a nice start in AA, with nearly as many walks as strikeouts, and a couple of home runs in 34 at bats.
Since I can't talk about one without talking about the other, Lars Anderson is also doing fairly well at AAA, after destroying AA for a month. So far Anderson is hitting .250/.375/.476 with a couple of home runs. I'd say the most impressive thing about his play so far in AAA is his approach - while his strikeout totals have been high, he's showing a very nice batting eye. The strikeouts are something to keep an eye on though - he's striking out in 30% of his plate appearances so far in AAA and even when he was hitting extraordinarily well in AA.