Just because something is a daft idea, doesn't mean it can't be done.

We sometimes need to do some housekeeping - like delete old files or list items or… yes, well, whatever you use Powershell for in a SharePoint world. Or it could be that your solution has "issues" for which you have Powershell solutions, but not the budget to transform into proper bug fixes. So you create a "how to" for the ITPro guys.

Idea: What if we keep the scripts in a list, and have SharePoint execute the scripts on demand? An announcements list (because of the multiline body field).

Warning! Let us be clear. This list needs to be locked down; if somebody creates a malicious script and you run it, I cannot help you.

First; we need to figure out how to start Powershell scripts from C#. Hit teh interwebs and the Googlie, and you may find jpmik's post: http://www.codeproject.com/Articles/18229/How-to-run-PowerShell-scripts-from-C. (Or MS' official answer at http://msdn.microsoft.com/en-us/library/ee706563(v=vs.85).aspx)

        public string RunPowershell(string powershellText, SPWeb web, string param1, string param2)        {
            // Powershell  ~= RunspaceFactory - i.e. Create a powershell context
            var runspace = RunspaceFactory.CreateRunspace();

            var resultString = new StringBuilder();
            try
            {
	// load the SharePoint snapin - Note: you cannot do this in the script itself (i.e. add-pssnapin etc does not work)
	     PSSnapInException snapInError;
                runspace.RunspaceConfiguration.AddPSSnapIn("Microsoft.SharePoint.PowerShell", out snapInError);

                runspace.Open();

                // set a web variable.
                runspace.SessionStateProxy.SetVariable("webContext", web);
// and some user defined parameters
                runspace.SessionStateProxy.SetVariable("param1", param1);
                runspace.SessionStateProxy.SetVariable("param2", param2);

                var pipeline = runspace.CreatePipeline();
                pipeline.Commands.AddScript(powershellText);

		// add a "return" variable
                pipeline.Commands.Add("Out-String");

                // execute!
                var results = pipeline.Invoke();

                // convert the script result into a single string
                foreach (PSObject obj in results)
                {
                    resultString.AppendLine(obj.ToString());
                }
            }
            finally 
            {
                // close the runspace
                runspace.Close();
            }
            // consider logging the result. Or something.
            return resultString.ToString();
        }

Ok. We've written some code. Let us test it.

            var runner = new PowershellRunner();
            runner.RunPowershellScript(@"
                        $web = Get-SPWeb 'http://server/web' # or $webContext
                        $web.Title = $param1
                        $web.Update()
                        $web.Dispose()
                    ", null, "New title", "not used");

if ($host.Name -eq "ConsoleHost")
{
	Write-Host 'If I agreed with you we'd both be wrong'
}