Yes or no, it’s your choice.
In a move likely aimed at thwarting EU complaints, Microsoft has changed the way IE 8 acts when it’s installed. No longer assuming that simply by installing IE you want it to be the default browser, it will instead present the dialog panel shown.
According to the IE blog entry:
we heard a lot of feedback from a lot of different people and groups and decided to make the user choice of the default browser even more explicit. This change is part of our ongoing commitment to user choice and control.
Bottom line is if there’s another browser set as the default the user will have to explicitly change it to IE via the new panel. It used to automatically be made default if you chose Express settings (instead of Custom) for installation, but now you get the choice either way.
This is a small change, but a welcome one.