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.