Interesting challenge... but I don't think I could devote the time... hmmm...
EDIT- so it seems I couldn't resist... working on it.. will release "something." Not sure how close it will be to the VB4 version, we'll see...
Awesome news, that would be great stuff!
I'm not a coder so I can't help much in coding but I will be happy to help with testing it out on my test forum and to add my suggestions etc.
Well, there are not many things that haven't been already done for vb3 but activity stream is one of those missing things.
I've seen on the other board someone claiming he had it done as the module for vbadvanced cmps but I haven't found contact to him neither his mod. There is one mod also not from vb.org that has some kind of functionality of following friends but it isn't exactly it and it's very messy.
The only mod existing for that is this one https://vborg.vbsupport.ru/showthread.php?t=264053 but it's for vb4 and the auhor says it cannot be ported that easily cause "it requires the new vBulletin framework, which does not exist on 3.8."
So there is no even basic functional activity stream mod for vb3.
I'm happy to hear someone will give a try and will make an effort to code it.