In my book there really is no reason to get anything more than an i5 750 except for E-peen. I have yet to come in contact with anything that this processor can't handle and since the absence of multithreading is the only difference between the 750 and any other i7 Lynnfield than what's the point?
I respectfully disagree. With certain applications where the processing pipeline is not fully utilised, having hyperthreading can increase usage of the processor, by fulfilling requests from other threads while the core is waiting on a particular thread (done by duplicating resources logically). In certain applications, this shows a marked improvement in application performance.
Tom's Hardware comparisoniXBT labs comparisonGenerally speaking, encoding and rendering apps get the most performance improvement from having HT enabled. If you do either of these 2 on a frequent basis, the additional cost of $100 or less (for an entry i7 over i5-750) is not that great compared to the cost of a new CPU+motherboard anyway (if you're upgrading from an older socket), and gives a significant improvement in performance.
However, I do agree that for the rest of the world, hyperthreading is not that useful.
Firstly, because OSes are not hyperthreading-aware yet, and can't differentiate between logical cores and physical cores yet. For apps that do not benefit from HT (especially those that take a performance hit from HT instead), running on 2 logical cores from the same physical core gives worse performance than running on 2 logical cores from different physical cores.
A hyperthreading-aware OS that is programmed with this difference in mind will be able to assign threads to logical cores more appropriately, depending on how taxed the physical core is. Right now we're not seeing this yet, but since AMD has plans to implement hyperthreading on their processors as well, perhaps we'll see this soon, and hyperthreading users can have their cake and eat it too (let some apps benefit from HT without other apps taking the performance hit).
Secondly, applications that benefit most from hyperthreading are typically encoding and rendering apps - not quite your usual 'normal consumer' applications. Even for some applications that benefit a little from HT (e.g. virus scanners, file archiving programs), the performance increase is barely noticeable for their typical usage scenarios, which are smaller-scale.
For your typical power user, the real benefit of the i7-860 over an i5-750 would be the extra speed bin - hardly worth $100, IMO.
tl;dr If you do lots of encoding or rendering, i7 is worth it. If you don't, i7 is probably not worth it. If you have an i5-750, don't bother upgrading to an i7-860. If you have lots of money to spend anyway or need epeen, buy an i7.
Looks pretty awesome though 

TWO?! i7 extremes?! WTF?! OMG awesome server boards!!
I would love to get an i7 but I got an i5 750 as well, but still this bakes cakes a lot faster than the C2Qs, even overclocks better.
lol I seem to see the letters 'AMD' in the darkness.
Wait... I failed.
http://img.xataka.com/2009/02/amd_istanbul_24_cores_500.jpg <-- quad-socket, 6-core Istanbul XD