I know it's a silly question but what is the official front and what is the back of the leather case of my Curve 8310?

The side with the raised strip is for the front of the BB. It makes a groove on the inside of the case for the trackball.

That is correct the raised strip is for the front screen of the BB, also it's where the magnetic piece is. Cases with belt clips, the phone always goes in screen facing the belt. To answer your questions the front is where it says Blackberry...

Haha well I'm glad I'm not the only one who was a little confused when they got their BB. It took me a day or two to finally figure out which side was which.