I'd been hearing
that the Mini was intended to contain the same guts as the S3 but just in a smaller frame, so as to be direct competition to the iPhone 5; however, details are coming out that may indicate otherwise:
Samsung to announce the Galaxy S III Mini tomorrow, leaked specs suggest an underwhelming device | Android and Me
- 4-inch Super AMOLED 800×480 display
- 1Ghz dual-core STE U8420
- 1GB of RAM
- 5 megapixel camera
This suggests more of an entry/mid-level device than a high-end iPhone killer. This could still be wrong, of course, but it would be disappointing if true.