fetching posts and showing on frontpage

I am having two sites viz. http://www.a.com and http://www.a.com/b
Now, these are two seperate wp installations, in the same /root where ‘b’ is kind of an extended vertical site of ‘a’.
I want to achieve the technique where I’d be able to show recent (or all that I publish) posts of B on A’s front page. The post should look like as it the usual part of A’s native posts.
For ex- if I post any topic title “my post” on B, then it should appear on its front page plus, it should also appear on A’s frontpage. Any help?