There are a whole range of integration options that customers have today between On Track and WebCenter Spaces. At the simplest level, you can create a page in your Space and embed the conversation list component of On Track within it. This would give users of a Space a list of all their conversation in On Track and the ability to launch a conversation pane by clicking a link. You can also use this approach to put conversation lists in the users home space / page. The next step could be to provide scoping of the conversation list, to have a list of conversations which is particular to each Space.
More advanced integrations are possible, depending on whether you are building and deploying custom taskflows within Spaces, or simply using Spaces using out of the box services. I would suggest starting by looking at the ability to embed the conversation list in your Spaces, which can be done via configuration versus true development. This capability is covered in the On Track developers guide, here: http://download.oracle.com/docs/cd/E20968_01/doc.1/e20959/toc.htm
If you have particular use cases you want to target we are happy to discuss them here.
Josh Lannin, Product Management, Oracle On Track