Well I have this very same question too and if you search the web many, many other people also. Perhaps "diesel vdub" you should think about not giving silly answers and instead read people's questions properly? Or as ElenaRaq suggests, if it offends you so much, just move on.
To be clear, if you use a new phone for say a week and fill it with contacts, emails, photos etc, and then connect to iTunes for the first time, you might (as I was and others were) only be given an option to Set it Up as a New iPhone, or restore from a previous backup of another device if you have other devices backup there. It is not at all clear from the iTunes platform or the web support and forums whether clicking Set up as New Phone wipes the device or not. Obviously we don't want to wipe devices. It's a simple case of requiring disambiguation - does "new phone" in this case mean a real new phone (which would suggest wiping the phone and setting it up as new) or just a phone that is new to the iTunes account (which would suggest it's fine, it would add the phone without wiping so you could go on to backup all its contents / sync etc.
In fact far from being "silly" this question seems quite difficult to answer. The web doesn't know. You haven't answered it either - instead choosing to dismiss it as "silly" and I just went into a Vodafone store selling and supporting new iPhones and they weren't sure at all. And have just spent half an hour talking to Apple Tech Support in the US directly on the phone, senior tech support people were consulted, various deliberations, and even they couldn't give a 100% guarantee that it would not wipe the phone. So it's odd, if it's so obvious as to be a silly question, than no-one can answer it. Don't you think?
You patronisingly told us to try reading the User Guide. Okay perhaps then you could explain exactly where in the User Guide this particular scenario is explained? I've looked and there's nothing. I'd be keen to know exactly what you think is "silly" about this question? If you fail to point to the user guide section that answers this query, fail to explain why the question is so "silly" and fail to answer it, perhaps you could apologise to ElenaRaq and all the many other iPhone users who are experiencing the same uncertainty and have the same question, who you have so arrogantly insulted with your rude and totally unhelpful answer?
Thank you.