What are the main improvements in suspension technology in the last 10 years?
I'd say the biggest change is the shift from coil and oil shocks to air springs. Even at the cheaper end of the market most bikes designed to go uphill will be using air shock suspension. Air suspension is lighter but in the past has performed less well and been more expensive. Over the years price has fallen and performance has improved.

The other big change is the amount of adjustment that can be achieved just by turning a dial. In 2002 I had to adjust the travel of my forks by taking them apart and moving spacers about. To change the rebound I had to use a different spring and to change the damping I had to use a different weight of oil. Now I have dials to adjust all three.

Lockouts that stop the suspension moving for more efficient climbing have also become widespread and much more reliable. Initially applying too much pressure to the shock while it was locked would break it. Now it will 'blow out' and switch back into non locked mode. Cannondale are taking this a step further in some of their new bikes which offer remotely adjustable travel on the fly from the handlebar.

Ps. this a great question and would be interesting for other parts of the bike. Bikes has changed massively since the birth of the sport.