I'm not a linguist, but I think the word 'share' implies there is mutual benefit and understanding. I can't really see how Sony taking an idea from Nintendo and implementing it in their own controller, with the goal of hurting Nintendo and helping themselves, could really be described as sharing.
But, hey, it is dog eat dog out there in the business world. Maybe there's nothing unfair about the fact that Nintendo pours alot of money into developing new gameplay ideas, only to have others reap the rewards. Fine. It doesn't really matter whether Sony is sharing or stealing the idea behind Nintendo's controller this time around...because, frankly, their motion control is a pretty pale imitation of the Wii's. The ps3 controller, while it sounds like it'll make for a good substitute flight stick, can't be used as a sword. Or a gun. Or a baseball bat. You couldn't use the ps3 controller to control RTSes or FPSes with a mouse-like precision. It just lacks that functionality, instead featuring the simpler motion control you'd find in, say, Kirby's Tilt N Tumble for the GameBoy Color.
So, while I do think Sony deciding to imitate Nintendo's idea so soon after they revealed it was a little low (a little desperate, a little pathetic), I don't think it's that big of a deal. E3 attendees weren't waiting 4+ hours to get their hands on a ps3 controller, after all.