Each Nation, Country, State, City, Province, or Village have there own laws that cover what is legal and illegal to share or download.
It is the users who make up the Gnutella Network!
So my suggestion is to check the Laws in your area to see what is legal and not legal to share or download.
You can also use the forum's search function, upper right between f.a.q. and home to search this topic further, as it has been discussed many times before.
Here are some links to get started with
Piracy
http://www.gnutellaforums.com/showth...threadid=25129
Is p2p file sharing legal
http://www.gnutellaforums.com/showth...threadid=26737
Avoiding Legal Charges
http://www.gnutellaforums.com/showth...threadid=23701
Porn
http://www.gnutellaforums.com/showth...threadid=25246
XXAA is watching, SPAMing the network, proof: (CycloCide)
http://www.gnutellaforums.com/showth...threadid=18230
Porn
http://www.gnutellaforums.com/showth...threadid=16808
The legal Aspect of File Sharing
http://www.gnutellaforums.com/showth...3195#post93195
Filtering Adut Content From LimeWire
http://www.gnutellaforums.com/showth...ighlight=adult
Additional Ways to Filter Porn from LimeWire
http://www.gnutellaforums.com/showth...ighlight=adult
Underage Nudity
http://www.gnutellaforums.com/showth...ighlight=adult
Kiddie Porn
http://www.gnutellaforums.com/showth...ht=kiddie+porn
Kiddie Porn
http://www.gnutellaforums.com/showth...ht=kiddie+porn