I was asked in a recent comment what I thought the best PLE software was (this following my comments about Ecto). I was going going to say it hasn't been built yet, and to a certain degree this is true. But if I had to point someone to something that actually does exist, I'd probably say WordPress, with any number of the plug-ins. Why? Well as this post notes, in most VLEs information is "caged in". But a system like WordPress really allows you to get content in and out fairly efficiently. That's most of what we want from a PLE. But see also Tony Hirst on PLE as platform touting the Benefits of Facebook and Zoho Notes (which I also discussed recently). If I could have my own private versions of those (on that, see Steve O'Hear on Facebook as platform) - and not be forced to rely on their benevolent hosting - they would also be strong candidates.