Companies receiving an Oregon media incentive rebate (OPIF, L-OPIF, R-OPIF and Greenlight) will receive a form 1099-G from Business Oregon (the state Economic Development Department).
IRS publication 525 regarding cash rebates (see page 29) addresses this.
In short, if companies are deducting the original expense from their taxes then receive a cash rebate from those expenses, the rebate is then taxable.