Was just reading an older article in Network World by Jim Duffy: Beware the single vendor as trusted advisor: Gartner. Essentially, Gartner has come up with another tool called the "Vendor Influence Curve" which describes the relationship between a vendor and a customer. The curve basically shows a tradeoff between a vendor's understanding of an enterprise's requirements and the value to the enterprise.
Initially, in the first few stages, there is value to the enterprise in seeking out a vendor that understands the customer's business requirements. In that case, then vendor can help the enterprise make good decisions. At some point, the customer starts to cede decision making power over the vendor, however, and at that point the vendor starts to make decisions in the vendor's self interest. It's Gartner's claim that for many customers, Cisco is at point 4 or 5 on the graph and needs to be reigned in.
Now, obviously, Cisco being who they are, you pretty much have to at least get their opinion on things related to networks. What Gartner is suggesting, however, is that you also get a few more educated second and third opinions. If a single vendor has become your sole "go-to guy" for buying decisions, you're probably making bad strategic decisions for your business and you're probably paying WAAAAYYY too much.
I have to applaud Gartner here for finally saying that the emperor has no clothes, and for Network World for reporting it. The fact is, both of these organizations derive a lot of revenue from Cisco as their own customer (Gartner for analyst services, and Network World for advertising and various other conference sponsorships). Good job, folks, the emperor is, in fact, buck naked.