function Split-array
 {

<# .SYNOPSIS Split an array .PARAMETER inArray A one dimensional array you want to split .EXAMPLE Split-array -inArray @(1,2,3,4,5,6,7,8,9,10) -parts 3 .EXAMPLE Split-array -inArray @(1,2,3,4,5,6,7,8,9,10) -size 3 #>

param($inArray,[int]$parts,[int]$size)

if ($parts) {
 $PartSize = [Math]::Ceiling($inArray.count / $parts)
 }
 if ($size) {
 $PartSize = $size
 $parts = [Math]::Ceiling($inArray.count / $size)
 }

$outArray = @()
 for ($i=1; $i -le $parts; $i++) {
 $start = (($i-1)*$PartSize)
 $end = (($i)*$PartSize) - 1
 if ($end -ge $inArray.count) {$end = $inArray.count}
 $outArray+=,@($inArray[$start..$end])
 }
 return ,$outArray

}

http://gallery.technet.microsoft.com/scriptcenter/Split-an-array-into-parts-4357dcc1