From time to time we are all working on one task, and then another one comes in that is higher priority. How can we handle this situation, such that our current work doesn't affect the new task at hand? At the change set level is the ability to suspend change sets.

By right clicking on any change set you can select "Suspend". Doing so will revert your source back to the level the source was at before you started making changes. Now you can work on your new task, without having to think about the changes you made in the previous task. When it's time to start back on the original task, you can right click on the change set and select "Resume". If in the latest task you made changes to source files that were also modified in the original task then you might have to deal with merge conflicts, if they can't be auto resolved. Afterwards your source is back to the state it was when you suspended the change set + the changes for the latest fix.

Other scenarios to use suspending change sets:
1. Prototyping different solutions to problems. For each prototype you can assign a unique comment/work item to each of the change sets.
2. Fixing Defects when Streams are locked down. After fixing each defect, suspend the change set to easily commit it when the stream is opened up again.