Some friends here on the Hyper-V team shared a PowerShell 2.0 script for getting a list of snapshots:

# List Virtual System Snapshots

#Obtain the VM name
$VM_Name= Read-Host("Please specify the name of the VM ")
$HostName = "."

#obtain the Msvm_ComputerSystem reference
$SourceSystem = get-wmiobject -namespace root\virtualization -class Msvm_ComputerSystem -filter " ElementName = '$VM_Name' "

#List the existing VM snapshots
Write-Host `n "    $VM_Name Snapshots :"
$i=1
get-wmiobject -namespace root\virtualization -class Msvm_VirtualSystemSettingData -filter "SystemName=`'$($SourceSystem.Name)`' and SettingType = 5”|
ForEach-Object{
    Write-Host "($i)" $_.ElementName
    $i++
}

For more info on how to use PS cmdlets see: http://www.microsoft.com/technet/scriptcenter/topics/msh/cmdlets/index.mspx

See also James O’Neil’s New and improved PowerShell Library for Hyper-V. Now with more functions and... documentation!

For all 35 sample Hyper-V PS1 scripts in a zipfile, go to: Hyper-V PowerShell Example Scripts.zip-download