Not much differ from other IT Administrator tasks since we don't perform or configure vMotion, HA, DRS, vShield, vDS & etc everyday. Same goes for VMs backup, performance report, other statistics gathering which also can be done automatically without Administrator intervention except when troubleshooting is needed but still, we wont do it everyday. So, if you configuring everything correctly, your day-to-day activity more or less can be the same like normal IT Administrator, do play with the guest OS & application.
This really is a question depending on size of your business. If you have a larger organization with lots to servers then this could have a big impact and admin. However, we have around 80 servers with 12 ESX hosts. I build about a server a month for various projects and it's really easy if I have VM Templates already made for the different OS's. Virtual technology can really make you life easy if keep all the templates set with your SNMP monitoring tools and backup software already installed on the templates. Also helps to keep all your servers updated with the latest patches for Windows and Linux.
Also, you can run various automated Health Check Reports on your VM's to simpify your day to day work. Also keep you in tune with your storage space. All the different variables that can quickly get nasty if you don't stay on top of everything.
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