Although you might not want to get stuck working on certain projects, that does not imply that the people on these projects are unhappy with their assignments.
Your IE Toolbar example is a good one. The team working on the IE toolbar is probably very small (how many devs are needed, one or two?), but it's used by a very large number of people. I think it might be interesting to work on a project with this very large user/developer ratio.
Google engineers to have some degree of mobility. If they get stuck on a project that they don't like, then they can eventually move on to something of their choosing.
Comments
Although you might not want to get stuck working on certain projects, that does not imply that the people on these projects are unhappy with their assignments.
Your IE Toolbar example is a good one. The team working on the IE toolbar is probably very small (how many devs are needed, one or two?), but it's used by a very large number of people. I think it might be interesting to work on a project with this very large user/developer ratio.
Google engineers to have some degree of mobility. If they get stuck on a project that they don't like, then they can eventually move on to something of their choosing.