Hand animation is just as crucial to believable character animation as is facial animation, and the new IPO driver functionality seems to lend itself perfectly to driven hand digit animation. However, it appears that the current driver system only applies to single IPO curves, not actions, as would be needed to cause the contraction of an entire finger, (where multiple joint rotation IPO's are generated whenever a finger contracts and is keyed). If one were to assign a control object that directly controlled the contraction of one or more fingers, it would be necessary for that controlling object to rotate more than one bone at a time, (hence the need for driven actions). Is this functionality intended for release in 2.40 or sometime in the future?
You don't need Ipo-Drivers but Action constraint (long time in Blender)
"Some Day, All Will Be Digital"