Tony Karrer has a great compendium of the posts at the heart of evidently a raging debate on the existential nature of personal learning environments. I'd start running down all the posts but geez, we'd be here all night. So I'll just pour my little cup of gas on the fire and then walk away.
Please stop using the word "learning" like its something that we can package and sell or even give away. You wanna know what a PLE is? Its called your head. Its called the sum of all your experiences, education, et al, and how that mix known as you interacts with the world. An aggregator is just that, a blog is that - they are opportunities for learning but they are not learning. A learning management system never actually managed learning. Why is this important? Because words matter - they color expectations and shape debates.
So lets just stop and figure out first what we the heck we're talking about....don't get me wrong, there is some important stuff in here and its called change management, and intellectual property laws and the evolution of corporate culture and privacy and more...so lets quit confusing the issue.