I held out. As much as I like dead tree CS books, lugging relevant ones around has become too much of a pain. Add to that the awesome offer from O'Reilly for $5 ebook versions of books you already own, and the ipad becomes irresistible to me.
I've just been holding out for a lighter version. I think the original ipad is just a bit too heavy.
O'Reilly sells DRM-free ebooks through their store, so they're unaffected. You load the ebooks onto the iPad using the usual transfer methods for media.
It's one of the nice side-effects of selling DRM-free books: they don't need an app that has the DRM baked-in -- you can use iBooks or any third-party reader.
A downside to this approach is not having an easy way to purchase books without a computer. iBooks has a great checkout experience and the only way O'Reilly could have something similar is by coughing up 30%. Tech savvy users can figure installing something like GoodReader and then downloading the PDF in MobileSafari and sending it over to GoodReader, but it's a UX nightmare. O'Reilly at least has technical users, other publishers are even more screwed if they want to go non-DRM.
Given that O'Reilly books are of technical nature, and you can't actually code on an iPad (unless you're using SSH/VPN), this is a perfect fit for the O'Reilly... you'll need a computer anyway.
Furthermore, I'm never on vacation and think, Oh, I'd love t read up on RoR... I usually already have the book.
I've just been holding out for a lighter version. I think the original ipad is just a bit too heavy.