The Pirates have promoted pitchers Bryan Bullington, Matt Capps, and Tom Gorzelanny; infielder Jose Bautista; and catcher Ronny Paulino. As far as these players' careers are concerned, these callups aren't terribly interesting - the pitchers will likely soak up a few innings, while the hitters will probably only get a handful of at-bats.
What's interesting about them is that Bullington, Capps and Gorzelanny aren't on the 40 man roster, so the Pirates will need to remove three players from the roster to make room. We'll know soon who those players will be.
This move also answers part of the annual 40 man roster riddle; it's pretty safe to assume that come November, Bullington, Capps and Gorzelanny will still be protected. This is no surprise in the case of Bullington and Gorzelanny, but it wasn't immediately obvious until now that Capps would be protected. All three players are deserving of roster spots.