[eru]

I am still searching. http://www.hull.ac.uk/php/cetag/1dshakes.htm confirms "the beginnig of the end" but does not give a source.

[lukeschlather]

http://www.google.com/search?hl=en&q=site%3Ashakespeare....

http://shakespeare.mit.edu/midsummer/midsummer.5.1.html#spee...

"That is the true beginning of our end."

Actually it seems like Shakespeare may be doing a bit of wordplay here, "end" looks like it primarily means "goal" as in "the ends justify the means."