I'm not going to go into the debate of which is the best camera on the market because that is an absolute minefield! There are so many good compact camera's out there right now, it would be near enough impossible to determine what is the outright best. I generally use Canon, be it my DSLR or the bridge camera for less demanding activities. I use my phone for candid, spontaneous snaps also. I certainly wouldn't compare different mobile phones camera's as a necessity for me to buy. Having a good camera on a mobile phone is always a bonus of course and the iPhone is plenty good enough for what its for IMHO. If the Nokia's are better and I don't doubt, then great. I don't own one and its really not something I would lose any sleep over 🙂
For me it's the other way around. A phone camera is very important. And when purchasing a phone, a camera is one of the biggest deciding factors. That's why I never considered HTC's phones, they have terrible cameras.
I like convergence devices and minimalism, but at the same time I like to take good quality pictures so having a great camera is important IMO. Plus the convenience of having a good camera always on you, always on, is great. The other day, I wound up in Wicklow mountains in Dublin, Ireland. I was not planning to go there, so even if I owned a DSLR, it would not be with me, so if I had a phone with a better camera, I'd have gotten much better pictures of the view.
If I was a pro, that did preparation or studio work, then I'd understand but spur of the moment, spontaneous pictures is all I take. And you're not going to take a DSLR or even a bridge to a bar or a party right? Or even to a concert or some event.
If Nokia released a phone with Android and 1" sensor, that really took better pictures than 808(1020 does not), I'd buy it.
As for the RX100, I'm not going to debate either, I just watched several reviews of it and many reviewers proclaimed it to be the best P&S on the market right now, so I'm just parroting their words.