wow.. talk about time stretching, this thread has been puttering along for two years and is suddenly back up near the top? hehe.
Anyway, some thoughts...
As Coer and Gallows have already noted, humans are capable of experiencing "slow motion" reality. It can be induced by drugs, by adrenaline, by practice, etc. There is probably a LOT of variety in the individual experience of the rate of time's passage.
To Exzoon, I think you have slightly misunderstood. Yes, Einstein established that the faster you move through space, the slower you move through time. However, no human being can move fast enough to actually experience that. Even experiments with atomic clocks in jets moving at Mach 3 only show microseconds of time difference over the course of a flight. And further, when Morpheus states that Agents are limited to rules, he doesn't mean that they are programmed with perfect muscles, thats just ... well, kinda silly. He means they experience the limits of programming language itself. Remember, its not that Neo can DODGE bullets, its that he doesn't HAVE to...
My take on bullet time is entirely different than any i see here. I see bullet time like the anti-skip protection on your CD player. When a CD player is reading the CD, its not like the needle of a record, moving over just one spot. It scans both ahead and behind, to see any scratches, etc. and find a way to keep playing past them.
Judging from the animations for it, I always figured that Agent's were using a similar technique. They have the programming capability to read the trajectory of a bullet, know where its going to be, and simply SKIP being there. Notice too, that Neo initially CANNOT do this. He sees the bullets coming and their trajectories, but he can't actually SKIP, so he just tries to get out of the way, and in the process actually gets grazed a few times. (Though I admit, Trin says "you move like they do." So maybe with out the slowmo, it looked just like the previous sequence wit the agent dodging.) However, this skipping ability would have its limits. A large number of projectiles arriving at close to the same time would leave no safe space to skip to. Hence, when Neo breaks out the electric Gatling gun on the helicopter (those have VERY high rates of fire, like a thousand rounds per minute!), they are not able to move skip fast enough to dodge (too many bullets to track trajectories on for the program).
Anyway, just my slightly different twist on the concept.