Wikipedia has a pretty comprehensive list of the guys who played and the guys who rehabbed in Portland if you're curious. This season, the Red Sox lead the charge with their young talent with the most players listed on the Top 100 Prospects. They have nine players, including Xander Bogaerts, who ranks #2.
#2 Xander Bogaerts, SSXander Bogaerts spent 18 games during the 2013 season with the Red Sox after Will Middlebrooks was injured. He showed versatility, performing well at both short stop and third base. He also showed veteran-like poise at the plate, especially under the pressures of the postseason. We'll most certainly see him in Boston this season, it's just a question of where. If no shortstop is signed between now and the start of the season, that's probably where he'll end up.
#30 Henry Owens, LHP
#33 Jackie Bradley, Jr, OF
#46 Allen Webster, RHP
#57 Gerin Cecchini, 3B
#61 Blake Swihart, C
#62 Mookie Betts, 2B
#86 Matt Barnes, RHP
#96 Trey Ball, LHP
Jackie Bradley, Jr. and Allen Webster both also spent time in Boston last season but didn't fare as well as Bogaerts. While Bradley started the season with the Sox, he was quickly moved back to Triple A Pawtucket to keep him from losing his rookie status. He showed quickness in the outfield and made some amazing plays, but his offense left something to be desired. In the 37 games played, he managed to bat just .189. A far cry from his numbers in Triple and Double A.
I really don't have much to say about Allen Webster. He wasn't that great in the handful of games he pitched with the Red Sox, but he showed potential. And he did have a pretty respectable season in Pawtucket, going 8-4 with a 3.60 ERA so I'm expecting bigger and better things from righty in 2014.
So there's your list of guys to keep a look out for this summer. I'm not sure just yet who's going to end up where but I'm sure one or two might land in Portland and maybe even show us something special. Pitchers and catchers report to JetBlue Park on February 15th.