only for peaceful, open and free research, as you can read from the project site :-) examples are the existing Search for Extraterrestrial Life and the Cancer research project. (In our docs that can be downloaded from http://sourceforge.net/projects/gpu both projects are presented)

if the project become succesfull an indipendent international gremium (e.g. the development team has people from about 10 different nations) will decide what plugins to sign. Signed plugins can then be installed to GPU.

a note on the random walk system for developers: it is very easy to implement it.

current Gnutella clients get a packet from one connection and
forward it to all other connections. The routing system is called
flooding and has lot of disadvantages.

future gnutella clients (if they get a packet from one connection)
they will choose randomly only one connection and forward it over that connection.

Packets will then travel randomly through the network and follow a pattern given from the heat equation (a partial differential
equation that can be often seen in diffusion processes). If you plot the density of packets in the network (where only one node sends out random walkers), you'll get a normal distribution.

Note that in the random walker system, the TTL constraint is needed.
However the routing table that keeps duplicate packets is not
necessary anymore. This was used to prevent packets travelling in circles.

I think if the team at Berkeley and Princenton say the new system is more efficient, we can believe it. To implement that change in clients is very easy; a small change to the routing method is enough (don't forward over all connections, but choose only one at random).