In a recent article, Lowell Cremorne touches on this very subject. The iPad would allow consumers to have the computing power necessary to run Second Life (or any other online worlds) but be completely mobile (and comfortable) doing so. If you could take your Second Life with you everywhere, wouldn't that make it more and more like your First Life?
Just to bring this situation back to something I can relate to - Before I had a Blackberry, I was your normal Facebook user. I'd check it 2-3 times a day. But since getting a Blackberry I constantly check Facebook posts, News Feed updates and all the other functions that Facebook offers. I definitely became more immersed. This likely could be the case with the iPad and Second Life.