One of the reasons for the delay is that there had been a chance that the Diamondbacks and Giants were being considered to open the 2011 regular season in Taiwan. When that fell through, several teams -- including the Cubs -- had to switch around some dates and the schedule is not finalized yet. It should be out later this week, and according to this tweet from Carrie, there's another reason:
Expect #Cubs to release Spring Training schedule soon. Team still finalizing details, which could include split squad weekend in Las Vegas
That would likely be the weekend of March 12 or March 19; based on other team's schedules released to date, the Cubs have a split-squad date on Sunday, March 6 already and I doubt they'd have a Vegas weekend the final weekend of spring training, as they are already scheduled to meet the Indians at Goodyear on Monday, March 28.
We also learn from another tweet from Carrie:
Expect #Cubs to name new pitching coach Wednesday.