Opera released the Opera Mini 5 and Opera Mobile 10 final versions.
New features on Opera Mini
Tabbed browsing
A visual Speed Dial
Opera Mini now remembers your passwords
A new, easy to use interface, optimized for both touch and keypad phones
A download manager
Opera Link, to keep you synchronized
Opera Mini 5 is recommended for devices with a display resolution of 320x240 or more.
Read more here
Am using both of them in my phone. i use opera mini when the data transfer amount counts, and using opera mobile 10 when am using the WLAN.