Shadowrun will use a friend-linking party system for ranked matches, yes, but developer FASA had to forgo the use of Microsoft's TrueSkill matchmaking system to implement the feature. In fact, according to Knuckles Dawson who had a chance to play Shadowrun, FASA has built its own matchmaking system from scratch. Microsoft's TrueSkill system does not allow friends to play together in ranked matches -- the explanation Epic used in its own defense.
It's hard to knock Epic for opting to go with TrueSkill. Heck, the system was already in place, and there were seemingly more important areas of development to focus resources on -- and Epic succeeded with an exceptional title. But there's no denying that the Xbox Live community has been upset with how the limitations of TrueSkill affect Gears of War. Epic is certainly considering these opinions, and it wouldn't be too far-fetched to predict that a future update will replace TrueSkill with an Epic-designed matchmaking system that supports parties.
[Update: We incorrectly identified Knuckles Dawson as an employee of Shadowrun developer FASA when he is in fact
an echidna an avid Xbox Live player invited by the FASA team to test out their title. The post has been amended.]