Can real-estate deductions be applied to W4 income?

[Anthony Z.]

When listening to the BP podcasts I often hear about different tax benefits such as:

• Itemized deductions related to acquiring/managing properties
• Home depreciation tax write off

Do these things lower the tax bracket of the income I get on my W4? Or do they lower the tax bracket of only capital gains derived from the real-estate itself? Can real-estate tax deductions be applied to the income I receive from my full-time job?