The Matrix Reloaded starts when Neo and Morpheus have already successfully freed quite a few people from the Matrix. The setting is supposed to be Zion, the last human city. The people of Zion look much like the crew of Morpheus' ship, worn out clothing and unusual piercings and hair styles. Some of the citizens have no plugs (natural born) and some have plugs (from the matrix). There are more ships as well.
In Reloaded, it is assumed that Neo is going to be able to do all of the amazing stuff he did in the end of "The Matrix", such as fly, jump into people, dodge bullets, run up walls, etc. The Wachowski brothers said in an interview that they wanted to be able to have a believable superhero movie, and "The Matrix" was a great way to make that happen. The special effects are going to be new, exciting, dramatic, and best of all, much, much better than in "The Matrix", if you can believe that.
There will be a car chase scene on a highway built just for the movie. The highway has since been torn down, it was in California near an abandoned naval base. Numerous explosions have been set off for the movie as well. Scenes have been filmed in tunnels and in high altitude airplanes. There is also going to be an elaborate dance sequence with hundreds of citizens from Zion. Yet another scene is going to include Neo fighting people with swords and other hand to hand combat weaponry in some sort of a mansion. It is my opinion that this mansion is owned by the character played by Lambert Wilson.
There also might be another person that can distort the Matrix like Neo, and he/she might be a double agent.
It is assumed that there will be a love story between Neo and Trinity, as you must have expected seeing as how Neo is Trinity's true love.
There is also suspected to be a scene involving replication of Neo and the agents, with 20 Agents versus 20 Neo replicas.