dramatic structures, system and a new post..

It seems like this site needs a topic to dicsuss so I'm bringing up this ;) My gaming group has decided to switch to weekly scheme but to keep the sessions very short, something like 1-1,5 hours. I'm now trying to find or actually design the perfect system for these short serial sessions as I'm convinced I won't find what I want. My main concern is how the dramatic structure can be represented when you only do a couple of scenes per session. There is clearly not enough time for a regular beginning, middle, ending with plot twists, build up, climax etc. You will have to spread the big dramatic structure over several sessions and weaken it's impact. I wonder however, if this is enough or if there must be smaller dramatic structures within every session. For me this seems very necessary but I can imagine that there are people who are happy with just playing loose scenes, seeing the bigger plot advancing over weeks. The obvious comparasion here is movies and TV shows but it still feels like the TV show can get more done than an hour of gaming. But as I stated I feel that a smaller structure is needed and this is were I come to the system. I want these small structures to have a big impact on the game and therefore represented in the system. I would like to have a system were I can say I want a tense action session with a cliffhanger and then put into the system and see it influence play. My question to you is what kind of meta-game mechanics do you think would fit this? (I'm aiming at some kind of minimalistic narrative point system, just wanted to clarify that I don't want other mechanics under the meta-game as it just takes away more of our little time..)