Sure. Just read the thread "iDEN and Opera Mini" at:
http://howardforums.com/forumdisplay.php?f=327
At some point you will need to register with Motorola Developer Network in order to download OpenJAL (I also had to download the driver for the usb cable I bought on ebay) that will deliver the opera mini 4.1 and other software to your i605. BTW I don't think you have opera; the default browser is Openwave. It is because you bypass the default browser that you don't get charged for data. I don't exactly surf on i605--I bookmarked a few mobile sites including cnn, bbc, etc. for quick access. For true surfing, I use my n800--at home with wifi, on the road with public wifi or iDEN.