Requirements management is considered one of the Achilles heels of Team System but that is not entirely true. Requirements management is a term that refers to a very broad set of different activities that concern the lifecycle of requirements life.
But there is a certain truth to this pre conceived idea, since Team System offer is (practically) non existent when it comes to requirements elicitation (which is widely confused with requirements management, since requirements elicitation is just a small part of requirements management).
When it comes to requirement management Team System is (imho) only ill served in the elicitation phased. And by that I only mean out of the box support, since there are offers from several partners to help you handle this shortcoming in Team System.
One of my my favorites for this task is the young TeamSpec from Personify Design, if you are more curious about TeamSpec you can watch Juan Perez talking about it oh Channel 9
Microsoft recently launched a Requirements Management with Visual Studio Team System White Paper explaining all the phases of requirements management, how they relate to Team System and some partner products that will help you fill the gaps that Team System currently has.
As a bonus the white paper also includes some information how this gap will be reduced in Rosario (Team System next version).