We've had this discussion several times here on mobileread. It really depends on the content of the advertisment. Don't forget that publishing houses have been putting ads in books for many years. You know that page that lists the author or publishing house other works? Or that excerpt for the next big blockbuster novel you read at the end of a book? Those are ads
and I'm ok with those. It's when you get into iAd or the new desire to bring the best of flash advertising (yes those) and mix it with even flashier video/etc that i start to get annoyed.
I picked up an issue of one of the new digital magazines by either time or newsweek for the iPad. I was turned off immediately when I had an embedded video ad for an airline pop up soon as I launched the magazine that i just spent like six bucks on.
But hell...corporations control publishing now and if there's some new way to exploit something to make more money they'll be all over it, hardly caring if they alienate the people that actually buy their content....
Ps typing on an iPad sucks. I don't know how they ever expected people to do actual word processing on this thing