Actually, this is already possible. On the list of wire posting if you click on the name link of the member who posted a wire messge ("By <name>") you will come to a list showing only the wire postings of this member. Also the wire messages by a single member can be reached via the entry in the activity river. Here the "wire" link opens the list of wire messages posted by this single member.

but my site is no twitter mate ;) I would like it if it can have comments on activity page.

Ah :) Then the question should be : ' How can to add Wire' posts comments on Activity page'

indeed how I can add wire post comments on activity page ?