This is not a tax cut. This is a tax deferral.
Normally, businesses depreciate capital equipment over a period of time, deducting only a percentage of the value each year. Allowing 100% depreciation in 2011 (it's too late for anything significant in 2010) simply means that a business can deduct the entire value in 2011.
If a particular item was normally on a 5-year depreciation schedule, the business would deduct 20% each year in 2011, 2012, 2013, 2014, and 2015. Deducting 100% in 2011 means that there will be no deductions for depreciation of that item in the remaining 4 years.
Depending on what happens to corporate tax rates in the interim, the business could pay more or less taxes in the long run. But, if they stay the same (and the business's average tax rate remains the same), there is no net reduction in taxes.
What's being proposed here, as you've pointed out, isn't really a "tax cut" at all.