Open Source has its place.
There are several layers to improving Gnutella. When the standard functions are Open Source, everyone would benefit by having optimal code. Everyone is the winner. The softwar needs to be modular so that if one company has a commercial offering, that there are hooks to provide extra services, services like crypto, authentication, XML for a particular type of information, preferring NEARBY copies in stead of far away copies..

Point is you make money on services provided not on services that everybody requires. When one Gnutella client is inefficient, everyone suffers. When the basic code is open and everyone contributes to modular code, service / servers are sold to legitimate users. Because serious money can be saved by having efficient P-P functionality (Intel is one company who understands that..)

One issue might be the License; it would need to be a license that allows for commercial use. (Your point) Mozilla with their three licensing scheme is one example of how this can be done

Thanks,
have fun
Gerard