Memeorandum and TailRank are both trying to aggregate blog and other edge content in near-real time and group content by topics/events. The result is a “newspaper for the blogosphere” that delivers breaking news to readers far ahead of traditional news services, or even Google news (the downside is that conversation swarms can occur around ultimately baseless stories).
Compare TailRank’s original interface from a post back in September to what they have now. In addition to a more usable interface, Tailrank has also started to group blog “conversations”, where different bloggers talk about similar topics, in a way I have not seen anywhere except Memeorandum to date.
Memeorandum is still better at breaking news – A headline on Memeorandum may not appear on TailRank until a day or more later – but TailRank is still much younger than Memeorandum and could catch up. And new companies like Australia-based Tinfinger (still pre-launch and sans content) and Blogniscient (profile) are gunning for this space as well.
The core back end difference between the services is that Gabe Rivera, the founder of Memeorandum, hand picked the original “seed” blogs with subsequent sources discovered by his system (guaranteeing quality but sacrificing breadth), whereas most of TailRank’s content comes directly from users who upload their favorite blogs in OPML format (the file format that most RSS readers like Bloglines and Rojo use to store feeds). The additional breadth of coverage offered by TailRank may be the cause of its lag behind Memeorandum in breaking news.