So a question I've had is, what do designers do at corporate companies (this includes sites of very large tech companies, such as Microsoft.com, etc.), given that there is so little that is quickly changeable? Do they have endless design projects where nothing is actually done except having meetings? Or what kind of iterations do they work on that may not be noticeable by the casual to moderate user?

Pretty much. I work for a pretty large software consulting firm and there are hours of meetings about simple design decisions. These are decisions that a recent grad out of university could make in about 10 seconds and make correctly. We have a team of designers that we work with that appear to have stopped using the web in about 2000, and their designs and work show it. However, they're somehow associated with the company and so continue to get the work despite the subpar work. Corporate BS basically.

Big corporations might have a big corporate slow-moving web site, but designers are sometimes set free on short-term ad campaigns. Like apple does. The big site doesn't change, but they incorporate cool html into it sometimes. http://lukedurrant.com/2011/08/apples-360-rotating-ipod-html...

Pretty much, yeah. As organizations become larger, they become more risk-averse, which means more meetings and more approvals. So a lot of the work done in big enterprises is just either getting agreement, or chasing down information.

they end up doing endless iterations of designs which mostly never end up in production, microsoft was done by paravelinc btw. Here's a real story of one of those big corps: http://dustincurtis.com/dear_american_airlines.html

Well, the great designers don't work at large companies (of course there are exceptions...). That said, a large corporation will also have hundreds, if not thousands, of intranet sites that are likely using the same resources. Some companies have a "web dev" group that handles all the internal and external sites. A lot of time is spent doing impact analysis, planning, and requirements gathering.