There's been a lot of debate about PLEs that I'm only just catching up with now.
Crudely defined, a PLE seems to be about moving away from the big cumbersome VLEs (yes, we're talking about you, Blackboard) and opting instead for smaller bits of technology (e.g. a blog, a Flickr account, RSS feeds, favourited web sites etc.) held together by, for example, a start/portal page like Pageflakes or Netvibes (My Yahoo!, iGoogle, and Microsoft Live are other types).
Is a PLE just a nice idea (see this post from the elearnspace blog) or a bit of Blackboard-bashing software (PLE Project - Bolton University) that's under development?
I'm not sure. Talk of PLEs feels like the (utopian) expression of a desire for a future beyond monolithic systems: something small, customisable, decentralised/user-centred, open-source, open to the hundred of new developments happening, eclectic, supportive of sharing, collaboration etc..
Here are some links to blogs on PLEs: