Has it ever occured to you that sub pages of your site rank higher than your main site? Well, i'm having a PR 1 for my main site, but the sub pages are having PR 3. Is it because I have more incoming links to my sub pages than my main site?
Yes it could be that you have more links to internal pages - this is the common explanation, although it always seems pretty unlikely to me, except for certain unusual circumstances. I have also found that the menu structure plays a role - certain navigation 'layouts' spread the PR out differently than others, which affects how PR is distributed in a site, and can lead to internal pages having higher PR than the homepage.
The navigation structure plays a big part. Have you got a link on your sub pages pointing back to your index?
Sure; that's completely common. If you have links pointing to subpages with one anchor text, and links pointing to the homepage with a different anchor text, you will rank better for the search that matches the anchor text used to the subpages.
There is also a known bug in Google that will give the high PR to an inner page, even if every link is to the home page. Can't say as I have seen it lately, but with the past 2 updates (the first buggy and frozen, the second using the same snapshot and barely more than a month later) it would not suprise me it is recurring. Here's a good thread, with links out to other discussions on it: http://forums.digitalpoint.com/showthread.php?t=61489
it all about the number of incoming links to that very page. Generally home page do have more links then any other page so it comes up. But it is not manadatory