It seems to be a trend for the moment to embed custom web dingbat fonts and use them as icons on web pages. But isn't it so that a screen reader will read those characters out load? So when it for example reads out a menu for a visually impaered visitor it could sound something like this (in this example the letter f would be a dingbat for an fancy arrow) f home, f about us, f contact.
I had a strong suspicion myself, so I just asked one of my colleagues (who is a JAWS user) to test it for me.
You're right: it does appear to read the keyboard-equivalent. Testing with the Wingding "snowflake" (which is 5 across, 3 down in this image), JAWS reads T. This would have the effect of reading letters in the place of the wingding.
I would suggest that the accessible way to provide this content would be to use images and provide appropriate ALT text equivalents (where necessary) and s for form elements.