Shadowrun Online will feature two major parts – the action map, where you (and your friends) do missions from stealthily infiltrating a secret Renraku research facility to punching the lights out of a major Aztechnology outpost with guns blazing. Hacking, magic and gunfights are all part of that and will be done simultaneously (so nobody needs to go for pizza while your hacker battles Black ICE for two hours).
The second part will be the legwork and mission preparation. This will happen on a city overview map, where you can try and use your contacts, skills or resources to gain info on the mission goal, acquire blueprints, bribe guards or prepare the right soft or spell for your endeavor. This will be closer to rolling the dice on an action and getting a short narrated outcome. Each of those actions will cost action points (and if you want to get better odds you may want to spend more action points on a specific objective).