One of the supposed benefits of enterprise (what that word really means reserved for another post, but a good place to start is here) Linux is that the included packages are "tested" and "hardened" (what does that even mean??!?) for the enterprise. The problem is, in the time it takes to test, these packages have grown quite old, increasing the chances that a sysadmin will need to replace them with software from elsewhere. For security reasons, and technical compatibility reasons, you're often forced to upgrade packages.

And you can't just grab updates from the vendor, because even the updates are really old, only marginally newer than the package that you're trying to replace. So you uninstall the vendor package, and either grab a package from elsewhere, or compile the source. And try to remind yourself what exactly you're paying for again...

An example? The just-release Red Hat Enterprise Linux 5 comes with an RPM for Firefox 1.5.x. What?

A common dismissal of Ubuntu (not typically described as "enterprise linux") is that "it's fine for the casual user, but not for the enterprise."
Frankly, its packages are more appropriate for the enterprise than any enterprise linux i've seen. For this reason alone I'm very excited about its increasing acceptance in the business community. Even if it starts at the periphery...