would either the IB and SB-E be worth waiting over the 2500k?
edit : or do people think its just a minoraddtion that will make litle change and is not worth the wait?
SB-E will be EXPENSIVE, completely pointless frankly. Ivy bridge will be rumoured, 20% faster than Sandybridge for quad core mainstream desktop stuff. We don't know where the 20% faster comes from, likely some of it from increased clock speeds, it has a 50% higher GPU processor count which will increase its speed in quicksync, it might be barely faster in terms of the actual cpu core, clock for clock.
If you have anything that troubles an overclocked 2500k now, then you want a 6-8 core chip anyway, making Ivy bridge pointless, a quad core Ivy isn't going to beat a 8-6 core SB-E, except in specific transcoding that quicksync works well in, even then you've got some quirks with having to use the IGP to use quicksync, though you'd hope they'll "fix" that little issue with Ivybridge chipsets.
Basically, the 2500k is a superb chip, SB-E and Bulldozer will beat it, SB-E comftably, Bulldozer probably half way between those chips somewhere.
If you make money on your home computer and are CPU limited, like rendering files and them rendering quicker makes you money faster, no reason not to get the best money can buy. For gaming, general use a 2500k will eat through anything you can throw at it. Spending silly more for a SB-E or waiting for Ivy isn't close to worth it. Bulldozer, maybe, it could be significantly better, only 1-2 months away, and faster and more future proof but most importantly, for similar pricing, well probably cheaper with cheaper mobo's and competitively priced chips.