Twitter and Jaiku do not _run_ on cell phones. You do not have to install anything to use them. They use SMS gateway which anyone can setup (if you have $50K+ a month to pay for the traffic, that is). My post was about apps which you have to _install_ on a phone! There's a huge difference between the two approaches.
I've noticed that most of the popular, succesful mobile startups use just sms/mms and a counterpart web site currently. Perhaps we shall see them 'evolve' as the years pass as mobile apps and then mobile web become familiar to 'regular' mobile users. Users will look back at the day you had to remember text commands and shortcodes just like we now look back at the command prompt.
For now I agree, apps are a pain and you should stick to the most well know interface of sms when you can. The 'fun' stuff needs apps but the chance of success is a lot lower currently.
With the right killer app, people will strive to buy the right phone.
Also mobile don't have another 'killer app' to come. Everyone wants something different from the phone, just like everyone uses the web for different things. It's about choice. Some want news, others want myspace or funny videos of cats. What mobile needs is to be easy to develop for and easy to find the apps that are right for a particular user. We need a yahoo or AOL that will guide the new users and show them what its possible to do on their phone.
(I can't find the reports that show the japanese usage of data currently. From what I remember most used voice and sms. Photos and email were also popular. After that usage for any function drops off into a 'long tail' distribution. The japanese users were all heavily using their handsets for different purposes. I'll see if I can dig up the report in the morning but it makes for fascinating reading)
twitter and jaiku are mobile startups, right?
and also: http://paulgraham.com/fixrazr.html