Marc Vidal has a letter in The Scientist urging scientist and funding agencies to increase efforts to map all human protein interactions. He suggests that different labs work on different parts of the huge search space (around 22000^2 excluding splice variants) and of course that funding agencies give out more money to support the effort. He makes an interesting point when he compares funding for genome projects with interactome mapping. I also think that the interactome mapping should be view in the same way has genome sequencing and that the money invested would certainly result in significant progress in basic and medical research.
The only thing I would add to my own wish list is that some groups would start comparative projects at the same time. Even if it takes longer to complete the human interactome it would be much more informative to have of map of the ortholog proteins in a sufficiently close species to compare with (like mouse). Alternatively some funding could go specifically to comparative projects studying for example the interactomes of different yeasts (it is easy to guess that I would really really like to have this data for analysis :).