Yes, this question seems to keep cropping up. See DeepCeleron's links in his prior post.
The main issue is that you will have a hard time find someone willing to trust you (unless you have a good reputation somewhere and are known in the bitcoin community). Once bitcoins are transferred, they cannot be revoked. Paypal, however, can be revoked up to 45 days after the transaction. So the person transferring bitcoins to you would be taking a risk that you would charge-back and disappear with his bitcoins. Why would anyone risk that?
The secondary issue is that it is against paypal policy to engage in activities involving currency exchanges. Some people consider bitcoins as 'currency'. I personally do not, but it is a grey area at best. And paypal has been known to cancel/revoke such transactions and lock accounts without much, if any, further explanation.