definite and indefinite articles in Beijinghua?

Here’s a post from John Sinosplice about an article he read in his studies which alleges è¿™, with a neutral tone instead of the regular fourth tone, is taking on the role of a definite article, and that 一, in the second tone from 北京è¯?’s 一个, is taking on the role of an indefinite article. I haven’t noticed this myself, but then again, I don’t get out much these days, being a lazy bastard who’s quite content to sit around wasting time online, and I’m not a real linguist, just a language learner.