what is outbound links and how does outbound links effects the PR of a page. It is really quite hazy to me. please help me with answers...
Outbound links are links that go from your website to another website. They could be defined as links to your own website as well, but then their definitions get weird. How do they affect the page they are on? They don't, at first. 85% of PR from any page is split amongst the links on that page (any page at all) and shipped off to the pages they link to. The final PR that you see for any page is derived from the links that are 'inbound' to that page and has nothing to do with how many links go out on that page. Long story short, get more inbound links to have any real effect on your PageRank. How an outbound link 'hurts' you (they don't, really) is that the link juice for that link will go to a different domain, instead of being passed to your other pages and recycled around your website. If a page has no outbound links (not to it's own site, not to another site), it is a 'dead-end' and gets removed from Google's PR calculation. This is the only way that the PR formula works. Outbound links are good, just make sure they are relevant and help your human visitors.
In my opinion too many outbound links can be considered as spam, if you have a forum and can't control every single post, set the attribute nofollow.
basically it is like this "The more OBL from your site , the less value your site PR will be ; vice versa" and about the penalization, i don't know exactly how it works with OBL