First impressions of Jaiku – a lot more tools, more fleshed out, I like the idea of comment threads on individual messages, it’s less about popularity per se, and more about a small tight-knit group (I think). The recent explosion of interest and use of Twitter seems to have people trying Jaiku as well, but from my few hours of use, the massive influx of users has left Jaiku with more speed problems than Twitter’s recent scaling and capacity issues.
However, the appeal of Twitter for me is its simplicity … it has very few tools and the posts (Twits) are primarily self-contained. The ‘@’ reponding has evolved socially, but I don’t imagine it’ll grow to get all that complicated.
More to the point, for me, Twitter is a sometimes food and I like my procrastination (or ‘continual partial prescence’ if you must) simple and no fuss.