I hate how Retina has now become a term of quality.
When its not that at all. Shrugh
My iPad isnt retina if i hold as close as my iPhone.
My TV is Retina if i walk 15 meters away from it.
And to answer your question. No the current iMAc doesnt look close to Retina when we talk about PPI. At the given distance from desk to screen.
And no there is almost nothing similiar to the bonding process and how the display is layered compared to lets say and iPad.
However with the new iMac they use the same techniques used to make/bond the screens on the iPad. That doesnt mean its a retina screen (pixel wise). That just means it uses the same type of tecnology to house the LCD etc etc.
People must not get those wrong.
Also if u listen closely to the verge video:
http://www.theverge.com/2012/10/23/3544356/apples-new-imac-first-hands-on
He cleary says the same tequnices. That means engineering wise. How the screen is housed, and how close the screen is to the display etc. But again, that doesnt make it retina. That requires a hell of alot more resolution. A resolution current gpus wouldnt be able to run without having lag issues.