Add-PSSnapin VMware*

Connect-VIServer 1.1.1.1

$vAppName = Read-Host "Enter the name of vApp (you may use regular expression)"

$vApps = Get-VApp $vAppName

if ($vApps -eq $null) { exit }

Write-Host "You really want to create snapshots in those vApps?"

Format-List -InputObject $vApps -Property Name

do { $Answer = Read-Host "[y/n]" }
until (($Answer -ieq "y") -or ($Answer -ieq "n"))

if ($Answer -ieq "n") { exit }

$SnapshotName = Read-Host "Enter the name of snapshots"

foreach ($vApp in $vApps) {

Write-Host " "
Write-Host "------------------------------"
Write-Host "Creating snapshots in '$vApp'..."
Write-Host "------------------------------"

$VMs = get-vm * -Location $vApp
foreach ($VM in $VMs) { New-Snapshot -VM $VM -Name $SnapshotName }
}