@Donald Remero: on Wiktionary “there’re” is listed as colloquial (http://en.wiktionary.org/wiki/there%27re) whereas “there’s” is not. Is this asymmetry real or is Wiktionary wrong?

Well, there is support for the asymmetry due to the fact that “there’re” is commonly avoided even in informal writing where contractions are permitted. I think for two reasons: 1) that when pronounced it is virtually indistinguishable from “there are,” 2) it is confused with “they’re” to the point that “there’re” feels wrong, seems wrong, etc. The OED does not, for example, indicate that “there are” is “frequently contracted” as it does for “there is.” That being said, “there’re” does follow the rules for contracting words, and it is used commonly, though not frequently.

…I can’t find an authority that speaks to this issue directly at all. Perhaps I should note in the answer that some would argue that it is non-standard. Regarding the Wiktionary, I’m not sure the value of noting it as colloquial if all contractions are not noted as such. I’ll try to keep my eye out for a published, authoritative comment on this issue.

The comment on it here (http://www.uhv.edu/ac/newsletters/writing/grammartip2005.03.23.htm) is fairly consistent with my initial analysis. I think the fact that this contraction “exists” and that it is used commonly cannot be disputed. I seem to recall learning how to use it properly in grade school. I’m quite surprised to find it being discussed as being so troublesome and of questionable status. (…learn something new every day!)

One more observation: There are indeed many quizzes and exercises on the web that deal with “there’re” without any notice of the idea that this contraction is somehow “non-standard.” I’m growing more certain of my opinion that it is perfectly standard, but frequently avoided for the reasons I site above.