The fact of the matter is is that

is is simply redundant

I would call it "native speaker error"

I'm glad this is annoying someone else (if you will forgive me!) - so frustrating to see so many people falling into this 'trap', and such educated ones, to boot!

Here are two useful links which explain it fully: http://www.casasanto.com/laura/documents/doubleis.pdf and http://itre.cis.upenn.edu/~myl/languagelog/archives/001123.html

It occurs to me that the post I made just now is altogether too technical!

In essence, people are misunderstanding a correct (though messy) construction and inserting a superfluous 'is' - basically, it appears, overthinking it.

So, 'What the problem is is that the government...' is a correct (if ugly) formation. The 'What the problem is' is the subject of the verb.

So people think that if they say 'The problem is' they must then add an 'is', and we get 'The problem is is that the government...' However, of course, the subject of the second example is simply 'the problem'. So it should read, 'The problem is that the government...'

I find it quite astonishing that this 'double-is' formation has achieved such prevalence in recent years, even amongst journalists and academics.

Never have I felt more Canute-like; I really must get over my frustration with this one, as I see absolutely no way of turning the tide!

This is similar to the "that that" problem, which I have myself found utilizing. Perhaps, if not in such a rush with emails, I would find the time to reconstruct my sentence to avoid "that that", though I don't find it difficult to understand when I read it myself. Perhaps others do.