Most jobs turn out to be very different than what you were told about in the interview. So your first task in your new job is to figure out what the job really is. Most people don’t do this which is why there is a whole cottage industry of people who coach for the first ninety days of a job (here’s a book and a web site for starters).

You must realize that each new hire has political motivations. It’s your job to uncover the politics behind your position so you can figure out what you should really be doing instead of relying on your official job description.

A good example of this situation came up in Fortune magazine this week. Garry Betty, CEO of EarthLink said, “Google only has three engineers working on Wi-Fi. [CEO] Eric Schmidt laughingly told me in a meeting that the best hires they ever did was when they hired those three Wi-Fi engineers and put out a press release. The market cap went up $10 billion.”

In fact it was never Google’s intention to be a huge Wi-Fi provider. But Wall St. Analysts loved the idea that Google hired some top Wi-Fi engineers. By hiring three people, the stock price went up significantly. Certainly enough to justify the three salaries. So in fact, these three engineers didn’t need to do anything. For these engineers to thrive at Google, they needed to understand this situation, and decide where to go from there.

So before you get giddy about your new job, don’t get too attached to the job you think you got. Spent the first ninety days figuring out what people really want from you but couldn’t tell you in the interview.

And then, instead of complaining about bait-and-switch, recognize that it’s part of corporate life – it is, in fact, very hard to predict exactly what someone might do once they get to an office. So just do the job that needs doing. If you do it well, you should be able to finesse your position into something you like in no time at all.