Blogger (can barely keep up with all the changes everywhere this week!) - a new "backlinks" feature (pointed out by my Magical Sheep pardner Truckspy). It's not really trackback. It's a bit of a fudge - what it does is to use Google's newish Blog search to search for blog posts which have linked to a particular post:
[Added 9 October:] It's a bit like Technorati's Cosmos for finding posts in blogs indexed by Technorati which have linked to a particular post of yours, except that it cleverly lists on your post page itself the titles to all those posts, with the ability to click the right arrow by a title to expand and see an extract from any of those posts (which does mean your pages take a bit longer to load), and you can click the arrow again to hide the extract. For long lists this can be cumbersome and time-consuming - it would have been better if there had been a single link to click that opens a new window containing all the individual links (which could in turn open in new windows). Or if they could at least offer the option to have a single link to open a popup, I'd have preferred that. No doubt someone will figure out how to do it...
You can turn backlinks on or off for any particular post, and you can also (if you're logged in) delete an individual backlink from the list with the trashcan icon.
It also produces a "Create a Link" link, which works via BlogThis by allowing Blogger users to create a new post which automatically contains a link to the post they want to link to. It's nowhere near the same as "true" trackback, e.g. it won't allow non-Blogger users to create a quasi-trackback link to your post and I'd like to be able to change the "Create a Link" text to something else, but it seems we're stuck with it. [Added 18 October:] I've since figured out how to change the "Create a Link" backlink text.
You can only turn on backlinks easily if you (1) have a newish Blogger blog, and (2) use one of Blogger's standard templates. If you have an old Blogger template, or use your own custom template, the help page supposedly contains a link to instructions on how to add backlinks to your blog, but that doesn't work (and the link actually goes to "not written yet" if you hover over the link text!). But I've figured it out and will post a howto about it soon. Probably tomorrow. [Edited 18 October:] Well it took a bit longer but I've done it now, and the Blogger help page link is now working too - see this post.
Meanwhile if you want to check out how it works on a blog other than Buzz, take a look at my introduction to Technorati tags post.
[Added 9 October:] One problem Truckspy has pointed out is that the linkback code, at least in my non-Blogger standard template, does funny things to your blog in Firefox (and, I've noticed, in Opera too - but not Internet Explorer... does this herald a Google/Microsoft linkup, I wonder...??). It stops you from selecting/copying the text on the blog page, not so good for my blog where I sometimes post code for people to copy/paste. In Firefox, it even stops you from copying what's in the address/location bar. Must be a bug - I've just written to Blogger about it and if you have the same problem, even if you have a new standard template, you might write them too. Oh, and I've noticed it intermittently mucks up scrolling your blog page with the keyboard too. Bit of a pain, that - hope they fix it or I'll be taking the code off soon! [Added 18 October:] They've fixed that now, great. And it's loading faster too.
Technorati Tags: Blogger, Blogger.com, backlink, backlinks, trackback, blog, blogs, blogging, blog tool, blog tools, blog addons, blog add-ons, Google, Google Blog Search, Blog Search, Blogsearch, Improbulus, A Consuming Experience, Consuming Experience