They're highlighting their new iPad-optimized Kindle Store for Tablets. That is clearly a shot back at Apple for the recent "eBookstore Armageddon". Given how close they were to releasing their web app, I'm a little surprised that they didn't play more hardball with Apple, though.
No irony intended, actually. Although the emphasis on the iPad here shows how successful Apple has been at making this a one-platform market either way.
I can now read Kindle books on any computer with a reasonable browser. I can't even read iBooks on my Mac. I prefer O'Reilly-style DRM-free PDFs, but at least I don't have to own an iDevice for the rest of my life to read my ebooks.
I was expecting a similar experience to this on my desktop as well. Loved the web app but wish the store was also optimized and didn't just dump me onto the main AMZN site ;(