What are the biggest threats facing Cisco this year?

Christopher,
I would say the largest threat the Cisco faces is the education of end customers on competing products. The down turn in the economy has changed the way a lot of companies make capital purchases. A few years ago when a networking project was given to an Engineering staff they would brainstorm on what Cisco models would fit the role. Now with smaller budgets Engineers are forced to look at what solutions will provide the best value to fit the roles. This may cause a fair chunk of market share to move to other enterprise class brands such as Brocade/Foundry or Juniper. There are other companies out there that offer the service and support like Cisco and has products that will do the same and in many cases better for a lower price point. The more people learn about that the bigger the threat to Cisco’s dominance.