Oil Reporter isn't that different from any other crowdsourced reporting app, technically speaking. I mean, in terms of raw functionality, it's not that different from, say, the app AT&T has its customers use to report dropped calls: Each report contains relevant information about the location, time and circumstances of the incident, which presumably help the recipient fix the problem.
Oil Reporter sends its decidedly more urgent reports to an organisation called CrisisCommons, which is dedicated to aggregating massive amounts of crowdsourced data to help NGOs, relief organisations and corporations and government agencies involved understand the scope and severity of a given problem. (And honestly, most stories about the Gulf oil spill are actually about changes in the known scope and severity of the disaster, right?)
Oil Reporter is free, obviously, and if you live on the Gulf Coast, or in any of the areas where the spill is projected to contaminate, you should be put off by its minimal set of launch features - CrisisCommons developed Oil Reporter first and foremost as a framework for other disaster relief apps, so features like native geotagging are on their way, hopefully (scratch that: probably) before the earth stops vomiting its blood into some of the most fragile ecosystems in the country. [iTunes via 148Apps]