By identifying your syndicated content with the standard feed icon, you're helping to…
- Eliminate confusion brought on by acronyms.
- Break down the international barriers.
- Bring feeds to the forefront.
Mozilla Foundation recently posted usage guidelines with accompanying FAQ for the feed icon. They've also branded two versions of the icon as being the canonical icons – one that you see here and a smaller 14×14 version that more closely resembles the original Firefox Live Bookmarks icon.
Both icons are now part of the download package offered here.