The specifications we have are:
- OS: Android Jelly Bean 4.2
- Display: 5 inch, edge-to-edge, 1920*1080 (full HD,441ppi ) Super AMOLED. There are some rumors saying SoLux Display will be used. This is unlikely.
- CPU: Exynos Octa 5450 A-15 (8-core: 4 A15 cores; 4 A7 cores) with Mali-T678 GPU (8-core). There are rumoring saying Qualcomm Snapdragon 600 (1.9GHz, APQ8064T, quad-core) will be used due to heating issues in Exynos Octa. This is possible. But as an Asian company, Samsung will probably still try to use own chips with more aggressive thermal management.
- RAM: 2GB. This is standard for high-end Android handset.
- Internal storage 16, 32 and 64GB
- MicroSD slot: up top 64GB
- Weight: 130-140g
- thickness: 7.5-8mm
- Battery: 2500-3000mAH, removable
- Main camera: 13MP, possibly with a dedicated button, and some fancy features
- Possibly with front speakers
Anyway, nothing is confirmed yet.
Update 15/03/2013 : Here are the official specifications of Galaxy S4!!