The following script generates an xml file with data from items using Sitecore PowerShell Extensions 3.3.

ExportItemToXml.ps1

# SPE 4.0 has upgraded the New-UsingBlock function to a cmdlet
Import-Function New-UsingBlock

$stringWriterDefinition = @"
    using System.IO;
    using System.Text;
    
    public sealed class StringWriterWithEncoding : StringWriter
    {
        private readonly Encoding encoding;
    
        public StringWriterWithEncoding (Encoding encoding)
        {
            this.encoding = encoding;
        }
    
        public override Encoding Encoding
        {
            get { return encoding; }
        }
    }
"@
Add-Type -TypeDefinition $stringWriterDefinition

function New-Element {
    param(
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [string]$Name,
        
        [string]$Value
    )
    
    $data = $null
    if($Value) {
        $data = (New-Object System.Xml.Linq.XCData -ArgumentList $Value)
    }
    (New-Object System.Xml.Linq.XElement -ArgumentList $Name, $data)
}

$items = @(Get-Item -Path "master:\content\home") + @(Get-ChildItem -Path "master:\content\home")

[System.Xml.Linq.XDocument]$jobsXml = New-Object System.Xml.Linq.XDocument

$itemsElement = New-Element -Name "items"
$itemsElement.Add((New-Element -Name "timestamp" -Value ([datetime]::now)))

foreach($item in $items) {
    $jobElement = New-Element -Name "item"
    $jobElement.Add((New-Element -Name "title" -Value $item.Title))
    $jobElement.Add((New-Element -Name "text" -Value $item.Text))
    $itemsElement.Add($jobElement)
}

$jobsXml.Add($itemsElement)

New-UsingBlock ($writer = New-Object StringWriterWithEncoding -ArgumentList ([System.Text.Encoding]::UTF8)) {
    $jobsXml.Save($writer)
    $writer.ToString()
}