Is there any useful book, website, tutorial, etc. which can help in learning LV-OOP? It fascinates me, however I have no idea where to start and I also have no foundations of OOP from other languages.
As to general OOP foundations it should be easy enough to find, e.g. for C#.
I don't know how much examples and stuff you get in the newer LV's (i'm on 2011 in todays project), but in the G# addon (link in my signature) you'll get 29 examples of Polymorphism, Interfaces, Inheritance and similar stuff. It adds references to LV-OOP and has some tools for automatic Icon generation, debugging, method cloning between classes and other helpful features. You can use it with normal LV-OOP classes also!
If you truly have no idea what OOP is but do at least know a fair amout about programming, try this first:
Next I'd read up on National Instruments white papers.