For years Apple's developers were allowed to register up to a hundred iPhone, iPad and iPod touch devices for app testing and ad hoc distribution, as long as they paid their $99 annual membership fee.
But large development teams have always been complaining how Apple's policy poses a serious problem with complex projects involving several dozen individuals who actively participate in the software development process.
These development devices are indispensable for testing purposes. For example, third-party developers routinely provide me with beta builds of upcoming apps and updates, which requires registering my device's UDID via the developer's account through Apple's iOS Dev Center.
Previously, developers could register up to a hundred iOS devices per account and now Apple is starting to double the number of devices developers can use to for ad hoc distribution to 200 iPhones, iPads or iPod touches per account...