Ping is Apple’s music-focused social networking service that’s available through iTunes on the Mac and PC, the iPhone and iPod touch, and now the iPad. It tracks iTunes Store purchases, and lets users tag songs and albums and comment on the posts their friends make.
Like Ping on the iPhone and iPod touch, the iPad version includes the ability follow other Ping users, view and comment on friend’s posts, purchase songs and albums from the iTunes Store, view upcoming concerts, and purchase tickets for shows.
Ping on the iPad matches the iPhone interface
Assuming you have already linked your Twitter account to Ping, your comments and Like tags will automatically appear in your Twitter timeline.
The Ping service is free to use and requires an iTunes Store account.