What that happens to be is the official, language agnostic, international symbol for "Here's my feed". If it looks oddly familiar, it's because it comes from the little "Live Bookmark" icon that pops up whenever you view a page with subscription links in Mozilla, and frankly, this is one of those cases where something is so blindingly obvious that it hits you like a truck.
See, the problem with all the various permitations of the orange XML/RSS links is that… well… nobody knows what the hell they are. Give them something like that icon (with the right tools to take advantage of it) and you've got something your Grandma could figure out.
i've already swapped the various old, crufty subscription links with this icon because, well, dammit it just makes sense. If you want copies to do it yourself, feel free to click on ye great honking big version and grab the download file yourself.
i get the feeling, we're going to be seeing more of these. (At least, i darn well hope so…)
Amen, JR. Let me add this: it would be outstandingly cool if people would format those links with CSS and put the icon in the background rather than directly linking around the image. That way, those feed links would be text links, which can be dragged out of a browser and dropped onto one's desktop, or into a friendly feed-collecting widget, or whatever.

[...] Me being one that is original and stuff, I went ahead and did what everyone else is doing. I switched out my old orange XML () chiclet for the new "universal" icon for "RSS fee". Check it out at the bottom. It looks nice, you see it in Firefox, and it should be able to confuse normal bystanders less than the three letters "XML". You like it? Want to use it on your site? Get the whole package here. The biggest benefit for me? The height of the icon is the same height as the "Add to My Yahoo!" chiclet at the bottom. Now everything looks copacetic. [...]