I did Taxing 07 in 41.50 seconds which I thought was pretty good, but it's nowhere near the Top 5.
What is your time on Tricky 07? (just curious...)
I have a partial solution that might explain how Fun 09 in 36 seconds is possible, but I can't figure out how to finish it. It's very tricky:
1. Pause and set release rate to 50
2. As soon as L2 appears at top of screen, pause and set release rate back to 1
3. Basically, we need to find a way to make lemmings turn around without using the Blocker
4. Make L1 start building in center of the flat land
5. L2 will climb the ramp that L1 is building
6. As soon as L2 falls off the edge of L1's ramp and hits the ground, immediately set L2 to a builder
7. L2 will start building but hit his head on the underside of L1's ramp
8. This makes L2 turn around and start walking to the left
9. By now, L3 has hit the ground and is walking right
10. Don't worry about L1 any more -- just let him fall in the green muck and die
11. You now have two builders left. L2 and L3 must build in the shape of λ to force all remaining lemmings to do an about-face and walk left -- (this is the part I can't make work -- the humps on the ground are critical to the placement if this method is really possible)