http://en.wikipedia.org/wiki/Vendor_lock-in
(As a side note I generally check the Wikipedia whenever I'm looking for a starting point on a 'concept' that is new to me. It's an excellent resource)
It's nice to see Moodle's success recognised, but despite sounding reasonably well informed about developments in e-learning, there were a couple of moments when you could tell the author(s) didn't quite 'get it' when it comes to open source:
the more prosaic part of the cheap and cheerful trend
Is Moodle's meteoric rise and fabulous community really prosaic? And while I do think that Moodle is both cheap and cheerful, I'll note for non-native English speakers that the phrase cheap and cheerful has slightly disparaging connotations, basically meaning that it's only acceptable because of its low cost.
In fact the author(s) seem to be suggesting that Moodle is simply a clone of existing proprietary VLEs.
that may start out as a poor brother to proprietary offerings, but gradually matches them in functionality.
Well, there is something to look forward to, Moodle gradually matching a proprietary VLE.