Is it ok not to have a button for a search box?

I was wondering if it was ever ok not to have a submit button (Ok, Go or Search for example) near a search box in Web pages.

I know that hitting enter is much faster and that it will perform the search.

However, is it an accepted convention for the average non tech savvy user or only for the tech community?

For example, the search box here at stackoverflow doesn't have a submit button, but I don't think anyone is complaining (and I sure don't).

On the other hand, someone suggested using Google as an example: would people notice if the buttons were removed?

I just started reading Don't Make Me Think by Steve Krug and he mentions that every search box should have something that tells me I can click on it to launch the search.

Your thoughts?

Why you should have a button:

• Not everyone knows they can hit enter, so you are leaving some less savvy people out in the cold.
• Some devices like phones and consoles may not have a way to submit without a button. The PC based browser is still dominant but don't assume it is the only way people access your site.

You may not have a button if (both conditions must be satisfied):

• Your audience is tech savvy (as on SO)
• You provide a visual cue that the search box actually is a search box
  • By adding text inside it mentioning it should be used to search
  • By adding an icon inside the box

Generally I would think that hitting enter is a shortcut to submit rather than the primary means.