Honestly, that sucks and is really unacceptable. We are talking about significantly changing the size of buttons/text between these two tablets. You should be able to design for both.

I don't think we are. Every iPad mini review I've seen so far says existing applications work fine and touch targets aren't an issue.

Font size is the only thing I've seen mentioned and there's a large element of that which is user preference (hence the adjustable fonts in iBooks, Kindle, Instapaper etc.).

The answer would seem to be sensible sized touch targets that work on both and adjustable font sizes which are actually beneficial to everyone regardless of what device they're using.

Exactly - Apple have always been completely crystal clear that your touch targets should be a minimum of 40x40pts. Your graphics themselves might be smaller, but the touchable area should be at least 40x40.

Text size, certainly, but touchable targets shouldn't be a problem assuming you're following Apple's guidelines. I appreciate that may not always be the case, but then you only have yourself to blame.

This question is about doing it in HTML5 though, so it's not like the iOS app guidelines are particularly followed.

Touch targets are the same size as on iPhone, so really should not be an issue there.

May I ask why it sucks? Genuine question. I don't get it.

(I'm asking in the context of someone who strongly appreciates "semantic markup" and "separate content from presentation".)