Generally speaking, it makes sense to send one MS Project plan to a single SharePoint task list within a single site. However, real-life MS Project plans can get very large, easily passing one-thousand tasks items. When this happens there are often multiple groups involved that may or may not benefit from see the entire project plan.
For this reason we are introducing the ability to share any summary task within an MS Project plan to a SharePoint task list. Furthermore, the IntelliGantt Add In for MS Project 2010 even lets you share any summary task to any SharePoint site (and one of its Task Lists).
This means you can have a single large MS Project plan and 'carve' it up up collaboratively (and metaphorically) so that your planners might see tasks within a 'Planning' SharePoint site or Task list while your engineering team might see tasks under a 'Executing' SharePoint site or Task list.
First up is sharing multiple summary tasks to multiple SharePoint task lists within the same site:
Next is sharing multiple summary tasks to multiple SharePoint sites:
Which configuration you choose is up to you. In one case it may make sense to use multiple tasks lists within the same SharePoint site if you project has well-defined phases, like a scrum for example.
For other projects, where perhaps you are working with a 3rd party vendor, you may wish to share a summary task with an external SharePoint site and other summary tasks with internal groups.
However you wish to share your project, and with whomever you choose, the IntelliGantt Add In for MS Project 2010 will be flexibile enough to meet your needs.