Nick's blog added to sample scripts: http://www.techphoria414.com/Blog/2012/March/Change-Item-Templates-With-Sitecore-PowerShell

Read-Variable returned items are now wrapped with PowerShell extensions

Author: AdamNaj

Data/serialization/master/sitecore/system/Modules/PowerShell/Script Library/Examples/Content Maintenance/Mass Change Item Templates.item

@@ -0,0 +1,79 @@
+----item----
+version: 1
+id: {50456B81-0FB3-4705-BC61-E6FDD2CF98A3}
+database: master
+path: /sitecore/system/Modules/PowerShell/Script Library/Examples/Content Maintenance/Mass Change Item Templates
+parent: {F25BF203-F58F-4F3C-B017-3ACD2F063479}
+name: Mass Change Item Templates
+master: {00000000-0000-0000-0000-000000000000}
+template: {DD22F1B3-BD87-4DB2-9E7D-F7A496888D43}
+templatekey: PowerShell Script
+
+----version----
+language: en
+version: 1
+revision: 1b5da6d3-8bcd-4f41-ba0f-ce0b04c88320
+
+----field----
+field: {B1A94FF0-6897-47C0-9C51-AA6ACB80B1F0}
+name: Script
+key: script
+content-length: 1505
+
+<#
+Based on Blog by @Techphoria414 - Nick Wesselman
+http://www.techphoria414.com/Blog/2012/March/Change-Item-Templates-With-Sitecore-PowerShell
+#>
+
+$sourceTemplate = get-item 'master:\templates\Sample\Sample Item'
+$targetTemplate = get-item 'master:\templates\Sample\Sample Item'
+$branch = get-item .
+$result = Read-Variable -Parameters `
+    @{ Name = "branch"; Title="Branch to work on"; Root="/sitecore/"; Tooltip="Items you want to work on."}, `
+    @{ Name = "sourceTemplate"; Title="Current template"; Root="/sitecore/templates/"; Tooltip="Template you want to replace."}, `
+    @{ Name = "targetTemplate"; Title="New template"; Root="/sitecore/templates/"; Tooltip="Template you want to use."} `
+    -Description "This report will replace template on all items in the tree with another template of your choice" `
+    -Title "Branch Template Replace" -Width 500 -Height 400 `
+    -OkButtonName "Replace" -CancelButtonName "Cancel" 
+
+if($result -ne "ok")
+{
+    Exit
+}
+
+$path = $branch.ProviderPath;
+cd $branch.ProviderPath;
+$targetTemplateItem = New-Object -TypeName "Sitecore.Data.Items.TemplateItem" -ArgumentList $targetTemplate
+Write-Host "For branch '$($branch.ProviderPath)' changing templates from '$($sourceTemplate.Name)' to '$($targetTemplate.Name)'"
+Get-ChildItem $path -recurse | Where-Object{$_.TemplateID -eq $sourceTemplate.ID} | ForEach-Object { $_.ChangeTemplate($targetTemplateItem); Write-Host "Changing $($_.ProviderPath)" };
+
+Show-Result -Text -Width 800 -Height 700
+Close-Window
+----field----
+field: {25BED78C-4957-4165-998A-CA1B52F67497}
+name: __Created
+key: __created
+content-length: 15
+
+20130902T111843
+----field----
+field: {8CDC337E-A112-42FB-BBB4-4143751E123F}
+name: __Revision
+key: __revision
+content-length: 36
+
+1b5da6d3-8bcd-4f41-ba0f-ce0b04c88320
+----field----
+field: {D9CF14B1-FA16-4BA6-9288-E8A174D4D522}
+name: __Updated
+key: __updated
+content-length: 34
+
+20130902T111843:635137175234032422
+----field----
+field: {BADD9CF9-53E0-4D0C-BCC0-2D784C282F6A}
+name: __Updated by
+key: __updated by
+content-length: 14
+
+sitecore\admin

PowerShellIntegrations/Commandlets/Interactive/ReadVariableCommand.cs

@@ -1,6 +1,7 @@
 using System.Collections;
 using System.Management.Automation;
 using Cognifide.PowerShell.PowerShellIntegrations.Commandlets.Interactive.Messages;
+using Sitecore.Data.Items;
 using Sitecore.Jobs.AsyncUI;
 
 namespace Cognifide.PowerShell.PowerShellIntegrations.Commandlets.Interactive
@@ -85,7 +86,12 @@ protected override void ProcessRecord()
                 {
                     foreach (Hashtable result in results)
                     {
-                        SessionState.PSVariable.Set((string) result["Name"], result["Value"]);
+                        object resultValue = result["Value"];
+                        if (resultValue is Item)
+                        {
+                            resultValue = ItemShellExtensions.GetPsObject(SessionState, resultValue as Item);
+                        }
+                        SessionState.PSVariable.Set((string)result["Name"], resultValue);
                     }
                 }
             });