Forgive me is this has been discussed (I haven't found any discussion in my searches.)
When Ben first takes Locke to see Jacob, there are a few frames where we see an older man sitting in the rocking chair; this is the same time Locke hears "Help me." Now that we know who Jacob is, what he looks like and what he sounds like, it is easy to conclude that the old man we saw in the chair was not Jacob. Nor (do I think) was it Nemesis.
Any ideas on who was sitting in the chair in that scene? And who said "Help Me?"