One of the major applications of Implicit Function Theorem is the lesson it teaches:
 
                          Locally, Manifold Theory = Linear Algebra. 

That is, we can perform our calculus as if it is linear algebra. Solving simultaneous equations, discussing about linear independence of coordinates, basis set and mapping from one manifold to another can be viewed as linear transformations. Infact by [Darboux theorem][1], in Symplectic manifold theory the linear algebra aspects is more prominent.  




 


  [1]: http://en.wikipedia.org/wiki/Darboux's_theorem