This talent plays a role in AoE tanking for feral druids. Swipe is often used in trash-pulls or gauntlets where speed is a factor and there are many enemies to hold. It is a useful talent for beginning tanks moving through dungeons but becomes less useful in end-game raiding.
The stealth increase in Cat Form is beneficial for sneaking past higher-level opponents, and can be very useful in PvP.
Edit
Patch 3.0.2 (2008-10-14): No longer increases threat generated in Bear form, but now increases damage done by your Swipe ability by 5/10/15%. 
