Yup. What happens is Google releases the source code to the manufacturers, who then determine which of their phones to develop it for. Each phone has different hardware, so different changes and tweaks have to be made to Android to install it. Then they make their customizations (Touchwiz for Samsung, Sense for HTC, etc). At this point, it is released to the carriers who do extensive 'testing' on their networks to make sure the OS is acceptable. Only then is the update released to the end user. More often than not, it dies at the manufacturer, who decides they don't want to update their phones.
Verizon is the worst btw for delaying(probably intentionally IMO) their updates.
Nexus 4 - Stock 4.4.2 Sweet, delicious KitKat.
Galaxy S Captivate - Currently stock again. Backup phone