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Garrett Lisi :  TOE without Strings
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The current epistemological status of String Theory is probably best grasped by comparing it with another theory devised in simpler times:  The Dirac equation was a clever example of a theory consistent with the axioms of both quantum mechanics and special relativity.  Some of the concepts involved in its interpretation may not have survived the test of time but it was instrumental in predicting the existence of antimatter and it helped demonstrate that any quantum theory consistent with special relativity would likewise involve antimatter  (which was duly observed, by  Carl Anderson, a couple of years after P.A.M. Dirac predicted it).
 
Similarly, String Theory is a quantum theory consistent with General Relativity.  Unlike the Dirac equation, however, it has failed to make any definite physical prediction so far.  Therefore, it's currently a legitimate target for critics who call it "unphysical" or "unscientific"  (arguably, a theory must have falsifiable consequences to be call "scientific" outside of the realm of pure mathematics).
 
Over the years, this state of affairs has slowly transformed "String Theory" into a general study of all possible quantum theories compatible with General Rekativity.  It's not just a theory of "strings" anymore.  It is hoped that, sooner or later, String Theory will achieve at least the same philosophical status as either Newtonian mechanics or Dirac's equation.  It may or may not turn out to be the advertised "theory of everything" but its logical structure would at least reveal some testable features of our physical universe.
 
The social impact of String Theory among the "community" of theoretical physicists can hardly be overstated...  An entire generation of many of the brightest theoretical phycisists have been lured by its mathematical appeal away from other pursuits.  Yet, nobody knows how relevant to physics the resulting body of knowledge really is.  So far, this has been a gamble of unprecedented magnitude without any definite payoff in sight.

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(2007-08-17)   The Magic of Euler's Beta and Gamma Functions
Gabriele Veneziano's 4-particle amplitude (1968).  Dual resonance model.

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(2007-08-17)   The Idea of a Fundamental String
Leonard Susskind.

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(2007-08-17)   Could that be a... graviton ?   (1974)
Joël Scherk (1946-1979)  &  John H. Schwarz.

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(2007-08-17)   No anomalies!  A  Theory of Everything ?
Michael B. Green  &  John H. Schwarz:  Superstring Theory.

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(2007-08-17)   Ed Witten's unification:  M-Theory  (1995)
"M"  is for  magic, mystery, matrix  or...  murky !

In 1995, Edward Witten combined into a single 11-dimensional framework the 5 competing 10-dimensional string theories and also the old 11-dimensional  Supergravity  of Joël Scherk (1946-1979).