According to various sources, including the Federal Times website, military members will be receiving a 3.9% raise in 2009. In addition, Congress has recommended that raises from 2010-2013 be 1/2 percent higher than the employment cost index. That would make military raises predictable and would likely outpace inflation.
Recall my "Really Painless Retirement Savings" post. By just setting aside your raise you'll save a significant amount of money changing your monthly budget.