There is also http://www.teknohama.or.tz/. Their events seem to be geared mostly toward beginners and not to people already in tech. A lot of the events are organized at awkward times for someone with a 9-5, participants are also very young, I'm 31 and was probably the oldest at one of the Samsung events that was held at Kinu. This is not necessarily a bad thing though.

I have very good contacts with my ISP (habari node), and the tech crowd here is mostly centered around the Arusha Linux User group, so it might not be super relevant for you if you're in Dar.

I suspect Dar would have more tech stuff going on - the ubuntu-tz LoCo seems to be mostly based in Dar for example.