I was listening to the latest .Net Rocks! podcast and one of their guests mentioned some posts about public speaking on Josh Holmes's weblog. I decided that I was interested in reading them so I slapped his blog URL into Firefox.
I didn't find the posts i was in search of, however I did stumble across a post which told me about a great video explaining Twitter. It's fantastic! It's all done using animation and paper and it's all "in plain English". The best thing about these videos (apart from the fact I found them entertaining) was that despite it being something I think my Mum would be able to understand there were none of the factual errors which seem to plague most "plain English" descriptions of technology.
If you'd like to check them out ("Zombies in Plain English" is great fun) head over to http://www.commoncraft.com/show.