The following script gets all the VMs that have connected CD ROM drives and in addition it also picks up VMs that may not have CDs in a connected or connect at power on state, but do have something in the IsoPath. The reason I like to remove the IsoPath data as well is that I have a report that I run that lists the datastores that VMs are on. If a VM has data in the IsoPath for the CD ROM this is picked up by the report, which is not what I am after. That and it makes the environment nice and tidy. 🙂

#Create a list of VMs with CD drives connected or have data in the IsoPath
$vmlist = Get-VM | ? { $_ | Get-CDDrive | ? { $_.ConnectionState.Connected -eq $true -or $_.IsoPath -ne $null } } | Sort
#Set CD Drives to Client Device, removing the Connected status and deleting the IsoPath
$vmlist | Get-CDDrive | Set-CDDrive -NoMedia -Confirm:$false

The same can be done for Floppy drives as well.
#Create a list of VMs with CD drives connected or have data in the IsoPath
$vmlist = Get-VM | ? { $_ | Get-FloppyDrive | ? { $_.ConnectionState.Connected -eq $true -or $_.FloppyImagePath -ne $null } } | Sort
#Set CD Drives to Client Device, removing the Connected status and deleting the IsoPath
$vmlist | Get-FloppyDrive | Set-FloppyDrive -NoMedia -Confirm:$false