Hi Gagan,
I suppose one could drum up a custom application to dig into Rally data. But as with all metrics, what are you trying to find?
One idea might be (for dev/qa resources) to query all the stories to find how many people edited or created a story for a specific feature? Then use a % to say DevBob worked 20% of his time on Project A, and 60% of his time on Project B. But, as a manager I should know that anyway.
Performance review would be wrapped around expectations and goals. Perhaps you could have a project that had each persons goals as stories and they could add tasks under them to show how they have progressed? Then during reveiw, bring up the stories, view the tasks and see how they have done?
These are some ideas, however I must say they are a reach, Rally is for project data. Performance reviews are different.
Good Luck, hope some of this helps at least!