It's interesting this cos the science suggests that any boiling will remove all the oils and that adding hops below 80C will maximise oil retention. But my experience suggests that late boil hops do add depth of flavour. And, for example, the hops that provide high myrcene levels deliver the myrcene flavours effectively with late boil additions and without any post boil hops, despite what science suggests. Why is that flavour not all boiled away? Is there some other science to explain this? I actually believe that 60 minute hops provide some hop flavour too. If you use certain hops this is particularly evident, Chinook being a good example. If you make a beer with just one hop addition at 60 minutes, a Chinook bittered beer will taste different to a Challenger bittered beer.
I found the following post on a thread on HBT about the use of hop teas made in a cafetiere after fermentation::
"Your statements regarding hop oil retention are very similar to advice that got from Vinnie Cilurzo of Russian River Brewing during one of my visits to the brewery. Vinnie advised me to focus my hop additions after fermentation. He said for me to chill the beer to drop the yeast, add hops and let them sit for one to two weeks.
As I can remember, he felt that the yeast absorbed some of the hop oils, thus flavor and it was essential to get the yeast out of the way to allow the hop flavor remain in the beer.
What I have tried with these experiments to combine the technique of getting the yeast out beer and extracting the hop flavor with hot water similar to a hopback that contains the aroma. I liken the making of a hop tea, to making my own hop oil extract that I add to the beer.
So far, I an very happy with the results. It has proven to be a very efficient way to add hop flavor and aroma to the beer."
I've added hop teas myself, at bottling time, and found they give a significant boost to flavour and aroma, but that it fades relatively quickly. It's good for beers you will consume within a month or two. Maybe MyQul and others can share their experiences. The benefit comes from leaving this hop tea addition to the last minute, when the yeast cannot remove any hop compounds. I've generally added boiling water to the hops, rather than water at 80C or below. I often do hop stands at 80C.
I'm still unsure about how to get the most from my hops, but I feel there is value in all kinds of additions, last 20 mins, flame out, 80C hop stand, dry hop and hop teas. They all achieve something different. The choice of hopping technique will depend on the beer you are making, the style, and what kind of hop flavour and aroma you want in that particular beer.