Powershell SPQuery to get documents created / modified within a specified time period (1 day in this case).

List Items within timespan.ps1

#Get SPWeb and Our List we are targeting.
$web = Get-SPWeb "http://spweburl"
$list = $web.Lists["List Name"]

#Build Query
$spQuery = New-Object Microsoft.SharePoint.SPQuery
#CAML Query Using a DateTime Value and and Offset of Today
$query = '<Where><Geq><FieldRef Name="Last_x0020_Modified" /><Value Type="DateTime"><Today OffsetDays="-1" /></Value></Geq></Where>'
$spQuery.ViewAttributes = "Scope = 'Recursive'"
$spQuery.Query = $query
$spQuery.RowLimit = $list.ItemCount
$spListItemCol = $list.GetItems($spQuery)

#Do Something with our ListItemCollection
foreach ($item in $spListItemCol)
{
  #CODE HERE....
}

I would recommend to not use "$list.ItemCount" since with more than 5000 modified items within the last day you would run into an exception. Else thanks for this example, helped me a lot