That's the ability that allows Inuyasha to break through barriers, isn't it? That really was a long time ago. =O

This will probably be very spoilerish.
Hmmm, let's see...
Naraku disappears for a while, but has the Band of Seven resurrected to wreak havoc on the Inu-gang. This lasts for nearly 20 episodes or so, then Naraku appears again in a new form, having finally cast out his human heart. He seemingly kills Kikyou, but she's later saved by Kagome. After that, the series starts winding down a bit as they find the final shard, Hakudoushi comes in as a new villain aiding Naraku, Inuyasha learns a new Tetsusaiga trick, Kagura becomes more rebellious, and the Inu-gang realizes where Naraku has placed his heart.

Oh, Kohaku regains his memories, and lots of other nice stuff happens.

That's all I can remember, and that took a while. XD