The knock on Jackson during the early parts of camp was his blitz pickups and blocking, which is normal for a rookie RB. Another thing to remember during those early parts of camp was that Jackson was thrown in there to try and stop Hawk and Barnett. They're no slouch LBs, and Jackson has some very tough blitzers to practice on. Also, Jackson has a great coach in Edgar Bennett who was an exceptional blocker in his day.
From everything I've seen and read lately, Jackson has shown some nice improvement there. Vs. Seattle on Saturday, I thought Jackson did well. Rich Gannon (Commentator for the Packers local broadcast) even made some comments that Jackson's blitz pickups and blocking has really improved. He has done well at reading and recognizing the blitz, and is willing to throw himself at a blitzer. The thing Jackson needs to work on now is his technique, which is very coachable, and Edgar will certainly show him the way. The key part I see is that Jackson is very willing. If a player is willing, he will be easier to coach, and in return show improvements much sooner.
For now, I see it as Jackson's job. He's continuing to improve and is the better RB talent IMO. Morency is still out too. When Morency does return, I could see the two splitting some series or switching off to keep the running game fresh. I'd actually like to see that since Jackson has been getting so much work this summer and he might wear down later this year.