I have set the streams to bump up on top when there is activity in it, however this brings some other, rather design flaws, than actual bugs.
See this scenario for example:
1. Five months ago, User A uploads five images on the stream.
Everything is great, stream is fabulous, etc...
2. Today, User B visits the User A profile and see that stream
He clicks on one photo from a bunch and likes it.
3. Now the frontpage stream show the same activity that is generated 5 months ago, saying
"User A uploaded 5 images in album XYZ"
- 5 months ago
Do you see the UX problem here?