Web designers will want to grab for developing interactive wireframes and website prototypes. The capability to demonstrate interactivity without building an entire mockup is certainly worth $9.99.
To get a look at more of the features that the Adobe Touch Apps offer, Adobe has a here.
How Will This Be Useful?
If you're offsite, you'd be able to make design changes on the fly without hauling a laptop. Yes, you could do that with a decent laptop, but a tablet is a less risky device to take traveling. Plus, outfitting your creative team with tablets rather than laptops is a huge potential cost savings.
There's also the question of price. While Adobe hasn't shared the numbers yet, it has promised that Creative Cloud will be inexpensive. Hopefully a recent graduate who wants to start their own freelance design business can enter the industry with Creative Cloud rather than spending thousands on a full professional Adobe software suite.