There has been an issue with the
SCEA and
SCJD exams database. Some people were sent certificates without their exams having been graded by Sun, and I believe others passed without receiveing certificates (as you indicate).
While their site was down for a while yesterday, they are aware of the problem at Prometric, and will hopefully resolve this quickly.
Eben Hewitt. SCJP, SCWCD, SCJD, SCJWSD for JEE 5, TOGAF 8 Certified Architect, author of Java SOA Cookbook (O'Reilly, 2009) and contributor to 97 Things Every Software Architect Should Know