Once you share the photo, they'll also be able to comment and like your photos without ever leaving the Photos app.
The new Photo Stream sharing feature will show up as an additional tab in your Photos app. You'll see the tabs you're used such as albums, events, and locations but you'll see a new cloud tab for Photo Stream sharing. Choose whatever photos you'd like to share from your Photo Stream which will create an album that you can name. Select the people you'd like to share those photos with and you're done. You can edit settings and change your share settings whenever you'd like straight through your Photos app.
Photo Stream sharing will also support commenting so the friends and family members you've shared your photos with can comment and like your photos directly within Photo Stream.
Photo Stream was demoed along with lots of new iOS 6.0 features at WWDC in San Francisco.