Twitter is suffering and Jaiku is showing off about how great that website is in comparison. They omit to mention two facts.
1. It’s (giving the impression of being) proprietary, interesting mainly to Nokia users (at the moment)
2. It’s better online (requires a browser to take full advantage)
Twitter is a mobile status tool of sorts
All text in italics is an edit following on from Petteri’s comment.
I think Jaiku is not proprietary at all: although we have our own Nokia S60 client, we have also 3rd-party mobile clients for practically all the Java-enabled handsets, Blackberries, and soon also for Windows Mobile. At the moment we have more than 20 3rd-party apps built on top of our APIs, ranging from mobile clients to iGoogle gadget and OSX + Windows clients. A more complete list can be found here.
You can also use Jaiku via SMS and IM (IMified, soon also via our own IM bot): browser is not required, although quite a few people use Jaiku with it.