Currently, it is my understanding that Iterations experience a burndown sync periodically (built into the system), or any time a manual sync in triggered. This results in Iterations that close without displaying accurate data on the burndown unless a member of the team manually syncs the burndown immediately prior to the Iteration closing. For large, international teams, this can be next to impossible.
This functionality gap can leave incorrect data once an Iteration closes - for example it may show 45/50 equally weighted stories complete, making the Iteration 90% complete, however there are only 45 stories listed in the Iteration and completion should be 100% (45/45). Adding a sync immediately upon closing an Iteration, or continuing automatic syncs after closure could remedy this problem.
This is important because it will allow agile teams to accurate monitor and report on their performance.
