it isn't the ipad
So here's what to do! Plug your iPad into your computer, Launch iTunes and click on the iPad tab. Then go to Applications and delete every Game Center game and Social networking. Then do a hard reset by holding down Power/Lock and Home. Then Go to settings -> Safari then turn on limit ad tracking. Then clear cookies, history, data and turn on Private Browsing. That's what helped me for this on my iPod Touch 4th Gen and iPad 3rd Gen.
iTechHelper
it really doesn't hurt to clean up your iphone/ipad, but it probably didn't fix the problem, either.
i just got hijacked by the same problem, and it seems quite repeatable, where my 2 idevices (iphone 3gs and ipad mini) got hjacked when trying to open a small business web site, and my 2 desktops (g4 and intel imac) didn't.
but switching safari on the g4 to pretend to be an iphone (under "user agent") got me to the x-rated sites. and also to a carefully crafted site that *looks* like the app store, but certainly isn't. it looks like they vary the destination, among a group of related pages. so far, every time i tried it from an idevice i was hijacked, although it's possible that the behaviour is randomized, and it may or may not target other smartphone platforms, since the same x-rated app is available at least for android. i didn't have the means to test it.
watching the screen more carefully, i could see the handoff to the mobile server (it helps to be using an ancient powerpc mac), and the redirect to the nasty site.
as best i can tell, the "problem" is on the server hosting the intended url, and you should take it up with them. (i tried berlin.de and cumhuriyet.com.tr but was not hijacked, possibly because the op was a few months ago.)