Story looks credible to me, leak of what I guess must be a UK carrier's remainder of 2010 seems to show that the N8 won't be available on that carrier in UK until October which seems quite late to me. Being quoted on omio.com (UK mobile deal comparison site).
Obviously the N8 might be available earlier on an exclusive on another carrier but I didn't have the impression that Nokia had signed it up as an exclusive (I'd think they'd need wider sales and frankly I think they'd find it tough to get a carrier to pay for a Nokia exclusive at the moment). I hope for Nokia's sake the release is earlier (Android 3.0 is out Nov), if it is that late they have to have an upgrade path to S^4 - or maybe they've been able to accelerate the development of S^4 and are going to drop S^3 and release it with S^4 ahead of official SF release and blind side us all 😎 ?