Asking the slashdot community to calm down... let's see how that goes. :-)
For the record, fedora has been my desktop distribution of choice for more years than I care to count and I do like the bragging rights of long uptimes, but I'm not worried about this change. It's clear that for those of us who care we can continue to use yum to upgrade and reboot when we see fit.
This won't affect any update that doesn't already require a reboot. The difference is that currently if you update a critical system library, everything that depends on that library has the potential to act in an unstable manner until the next reboot occurs. This change says that if you're updating one of those libraries, the update doesn't actually happen at package install time, it gets scheduled to occur on the next reboot. That's it.
I think the core of the issue is that we don't have good metadata to label "critical system library". As the feature wiki page says:
We also differentiate updates of 'OS components' (which we want to do in this offline fashion) from application updates and installations, which should still be possible from the UI without restarting the system... The initial heuristic is that a package is considered an application if it installs a desktop file that is shown in the menus.... This is not perfect and can be refined when additional metadata becomes available.
This sounds overly inclusive to me and implies that the update on any package without a desktop file will be delayed until reboot (by default).