I started using Google Charts a few weeks ago, and I have to say: it's pretty stellar. You can create bar, line, or pie charts with multiple colors and data sets using a simple HTTP GET. The names of the query parameters are kind of... trite... but overall I think the API is very user-friendly. I'm a fan.
Of course, the API does have one problem: it requires me to send all of my data outside the IBM firewall. Perhaps you hadn't noticed, but the IBM Corporation employs a lot of lawyers, and said lawyers get very uncomfortable when you start talking about sharing company data with servers owned by our competitors. It's unlikely that Google is employing a bunch of people to read through its server logs, find requests originating from its competitors' servers, and muse about their significance to Google's management team, but lawyers are paid to be paranoid, and ours are very good at their job. The net of this is that any IBM application that uses Google Charts and is not an obvious demo must be reading from a public data store.
Assuming that Google is in no rush to appease third-party developers using a service that doesn't generate any revenue, I'll be writing my own legend generator in the near future. I'll post the code once it's complete.
 I guess they're a competitor. I can't think of an area where we compete with Google directly, but my inner lawyer is telling me that once a software company reaches a certain size, it automatically becomes a competitor, regardless of its current investments.
 The Terms of Service explicitly denies such activity.