For those that have been using Cisco IOS 12 forever, you may not have realized that Cisco has begun rolling out IOS 15. Although there are a lot of technical changes and features that are being introduced, IOS 15 introduces a new licensing scheme that may throw old users for a loop.
Previous versions of IOS were bundled in release types that included software features Cisco deemed suitable together. For example, the Service Provider release included various routing protocols and other features Cisco thought service providers were most likely to take advantage of. It lacked some of the features included in enterprise versions for the same reason.
IOS 15 will ship as universal software images that include all features. If you're tired of hunting through long lists of feature sets to find the right image to download, you'll be really happy with this change. Additionally, your entire infrastructure will use one image. That should make deployments a lot easier.
To access the features you need, Cisco will be selling Software Activation Licenses. Each license is assigned to a specific device and can only be used to activate features on that device. The trade-off for maintaining a single image across your infrastructure is dealing with licenses for each of your devices. Fortunately, upgrading IOS does not require a new license.
Finally, if you're one of those network admins that used your CCO access to download images you hadn't actually paid for, you're ability to do that is going to disappear.