A few days ago I came across this bug in bugzilla. Kevin Gerich has changed the Fx default theme’s so-called alert icons:
Alert icons for Fx default-theme Winstripe, source: bugzilla

New alert icons for Winstripe (Deer Park)

From Comment #03 on this thread is getting really interesting. Dean Tessman provides a link to an MSDN-article, where the usage of Message Box Types and their graphical symbols are pointed out.
According to it, the usage of the question mark message symbol is not recommended (any longer):

[…] “The question mark message icon is no longer recommended, because it does not clearly represent a specific type of message and because the phrasing of a message as a question could apply to any message type. In addition, users can confuse the message symbol question mark with Help information. Therefore, do not use this question mark message symbol in your message boxes.”

Honestly, Brushed has never included a real information icon, it has been an information icon with an exclamation mark.
Here’s the “Confirm Close” dialog for a window with multiple tabs open in version of Brushed:

Brushed alert with question icon

Current make-up of various message-boxes with question icon

So this is the choice between the two following appearances:

Brushed alpha alert with warning icon

Optional new appearance of message box with a warning icon (Brushed alpha)

Brushed alpha alert with message icon

Chosen new appearance of message box with a message icon (Brushed alpha)

The Apple Human Interface Guidelines don’t give a good deal of information on this. The most useful information there probably is not to

“[…]use a caution icon for tasks whose only purpose is to overwrite or remove data, such as Save or Empty Trash; too-frequent use of the caution icon dilutes its significance.”

Therefore I decided not to use warning icons.
Anyhow, as a consequence of the articles above and of my own thoughts on it, I will not include the Question Alert Icon in Brushed any longer and simultaneously change question icons in dialogs to message icons. Perhaps I’m gonna go back to the old behavior in a follow-up version of Brushed if there are good arguments against this action.

Please leave a comment if you are not going along with this (upcoming) change…

Update 2005-10-14: By testing first beta of upcoming Brushed, I have changed my mind. I will make use of warning icon in this place. It’s the correct one and I’m not getting annoyed or tired of.