From what I know, the OPC is a 6-month course for POTC graduates. They get their regular rank as 2LT after being "recognized" (about 3 months). While the OPC is also conducted by the PA's Officer Canadidate School at TRADOC in Camp O'Donnell, it is different from the Officer Candidate Course.
The OCC, on the other hand is a 1-year course, open to qualified college graduates, whether or not you had any prior military training.
Currently, OCS has 3 OCC (OCC CL "KASIDLAKAN" 35-10, OCC CL "MASIKAD" 36-10, OCC CL-37) and 1 OPC (OPC CL 57-10) classes ongoing. Kasidlakan is slated to graduate around March 2010 with Masikad following suit by August.