I was not able to find a mentioned search engine, but I was able to make it myself with a help of Google Custom Search. I made a custom search engine with *.edu, *.ac.uk, *.edu.au and so on sites and domain zones, 145 in a total at this moment. From my point of view that search engine gives much better result pages, than an ordinary search. Also, the search index is almost spam-free and paid content -free.
There is a feature, that allows one to inspect what sites are included in the index, to comment them and to vote for or against them (to purge unrelevant site from the index, for example). Also, everyone is welcome to suggest new sites using a special form on the site. In short, it has all very basic machinery needed to make such scoped search engine to be community driven.
Try it at http://neatserpent.com/
Give me your feedback, please.
Do you find it helpful and better than ordinary search engine?
Would you use it?
Please, spread the word, if you like it.