Smart cards are defined in ISO 7816 standards. You need to buy those from ISO, but some pages have overviews on what is in those standards. There is a PDF preview (90 pages) available from IEC.ch Webstore.
PC/SC Workgroup defines the PC/SC standard that is used on windows, but thanks to PC/SC-Lite software also on Linux, Mac OS X and BSD. You can download all parts of the specification.
Important standards are:
- PKCS #15: Cryptographic Token Information Format Standard
- PKCS #11l: Cryptographic Token Interface Standard
- PKCS #7: Cryptographic Message Syntax Standard
Personal Identification Cards (PIV) it an upcoming standard in the USA. NIST has a document with details.
OpenCT implements drivers for several smart card readers. OpenSC can use OpenCT directly without the need for an additional middleware, and this combination is preferred by some authors and tested all the time, works perfectly.