Nikon DSLR's level of weather-resistance?

I'm ordering a nikon D7000, which has weather-resistant seals like the d300s. What will this protection be useful against, a humid day, a slight shower, a downpour, a drop in a puddle, or full a full submerging for a length of time?

The D7000 has basic weather sealing. It is NOT on the level of the D300s. The D7000's sealing will protect it from a slight drizzle and a dry dusty day only if the lens stays on. If you want tank like sealing get a D3 series.