Via LaVelle Neal of the Minneapolis Star-Tribune:
Hendriks has been poking around the Twins' system since being signed as an international free agent from Australia in 2007. The last two years, he's been given some starts for the big-league Twins, with pretty poor results (overall: 2-13, 6.06 ERA, 1.59 WHIP).
However, he's got a pretty good arm and has had decent results in the minor leagues (2.99 ERA, 1.108 WHIP in 580⅓ total innings, 100 appearances, 98 starts). It seems likely that the Cubs might be looking at him as a reliever, rather than a starter; guys like this can sometimes convert to be decent middle-relief options.
With the move, the Cubs' 40-man roster now stands at 38. If he makes it back to the big leagues with the Cubs, he will become the Cubs' first-ever major-league player from Australia (Ryan Rowland-Smith pitched in the organization at Iowa in 2012).