That's a delicate question, because I know it was the subject of many deliberations of the Expert Panel on Equalization in 2005-06, as Processor Béland alluded to.
It's true that the moment you include some types of revenues in the formula to determine the entitlement of equalization to provinces, it provides a disincentive to that tax base growing, because otherwise, if they grow or allow that tax base to grow, it diminishes their entitlements for equalization.
But I think there are broader incentives at play that provinces should take into account when deciding to develop—or not—certain sectors than just revenues that they could forego from the federal government, such as jobs for their citizens.
However, it's true that including some elements in the formula for equalization can have perverse incentives.