In my experience, it's a lot easier to get stuck in a niche in a small company. In large companies, internal transfer is much easier then getting the same job externally. In one place, we had an applicant for an Administrative Assistant in the IT department who basically wanted to get a foot in the door for when we had programming positions open. That was surreal.

A small company often needs you for the job you were hired for, meaning that transfering you creates a hard vaccuum. In a larger company, this is less so due to size of teams, more mature organization, etc.

There are many benifits to working at either a small or large, that's a whole other debate. But if you find you like the large organization culture, you'll most likely have much more flexibility in position once you start. Oh yeah, and usually switching internally doesn't provide the same salary change as getting a new job, so that may be a factor for your later carrier growth, especially with the recent slowdowns in the tech sector.

=Blue
...you might be eaten by a grue...