Marc,
Count me as definitely intersted in some spy rules. I've tried adapting a few pulp sets myself, but there always seems to be something missing. I think I've narrowed it down to the investigation aspect and clue gathering leading to a climax, and the reliance on small 1-2 figure teams for spy games (Bond + femme fatale, Avengers, Man from Uncle). Most of the skirmish pulp sets seem to focus on larger groups (if you include the grunts/red shirts) and clue mechanisms are typically for a goal in the present scene, not a connected campaign.
For me, the perfect spy game is played out over several scenes/games typically bouncing between exotic locations (think Bond movie). Each scene has the opportunity for action and clue gathering and when you gather enough clues it leads to the climax. With multiple groups I've usually had to use some hand-waving to justify all the factions' presence for the end-game (other groups tail the clue leader or something). If the linked clue/investigation mechanism can be accomplished cleanly in a skirmish game I think you'll have a good base mechanism for spy romps and detective stories.
Tim