Right from the faq:
Why does the world need Nutch, when search engines are free? Search
engines are free to use like television is free to watch, but, like
television programming, search results are subject to manipulation by the
interests that control them. The only way one can be certain that search
results are unbiased is if the technology which computes them is public.
Nutch seeks to make high-quality search technology freely available.
How can a non-profit afford to run a search engine?
Nutch is primarily a software project, not a service. Large scale
deployments of Nutch will probably be run by commerical interests separate
from Nutch, funded by advertising or somesuch. If the Nutch software is
good enough, perhaps existing major search engines will use it in place of
their current closed source code.
The Nutch project itself may choose to host small-scale demo system, so
that folks can see that it really works. This will require only moderate
funding. The Nutch project may never host a full-scale deployment for folks
to use as their everyday search engine. We’ll leave that to
commercial ventures that can afford it.
Will Nutch ever be as good as other search engines?
We hope it will be better. With developers and researchers from around the
world helping out, we hope to be able to surpass the quality of what any
single company can do.