It's always unfortunate when people recommend putting electronics in rice, rice is dusty and makes for a rather poor desiccating agent. It wont dry out your N900 any quicker than if you just put it on your kitchen table.

Wet N900? Remove the battery, strip it down to pieces, dry each part as best you can, then hit each part with a hair dryer or put it all in your oven at a temperature of not more than about 50 degrees C until you are convinced that it is utterly dry.

Once you are convinced, don't be. You've probably still got moisture underneath the surface mounted IC's. Pull off all the metal covers and hair dry it for another half hour or so. Then leave it all for half a day or so and let nature do what you might not have.

After this, if your N900 works, it works, if not, it probably never will.

Don't use rice, you would get far more benefit just sticking your N900 on a sunny windowsill than you ever will by submerging it in rice.