$TaskName = "20071029-AllRejectedDuring"
$SqlServer = "SQLDEV01";
$SqlCatalog = "MyData";

# Get the T-SQL Query from .SQL file
$SqlQuery = Get-Content (".\" + $TaskName + ".sql")

#Write-Host ($SqlQuery) -foregroundcolor "gray"

# Setup SQL Connection
$SqlConnection = New-Object System.Data.SqlClient.SqlConnection
$SqlConnection.ConnectionString = "Server = $SqlServer; Database = $SqlCatalog; Integrated Security = True"

# Setup SQL Command
$SqlCmd = New-Object System.Data.SqlClient.SqlCommand
$SqlCmd.CommandText = $SqlQuery
$SqlCmd.Connection = $SqlConnection

# Setup .NET SQLAdapter to execute and fill .NET Dataset
$SqlAdapter = New-Object System.Data.SqlClient.SqlDataAdapter
$SqlAdapter.SelectCommand = $SqlCmd
$DataSet = New-Object System.Data.DataSet

#Execute and Get Row Count
$nRecs = $SqlAdapter.Fill($DataSet)

Write-Host ($nRecs.ToString() + " Records retrieved.") -foregroundcolor "Cyan"
$SqlConnection.Close();

if ($nRecs -gt 0)
{
  # Do Stuff
  $DataSet.Tables[0].Rows[0][0]  #Print first data element
}

The connection is using Integrated Security for simplicity, it wouldn't be difficult to switch to UID/PWD instead.  Also, I put the SQL in a .sql file (flat text) to make life easier; you could also put the statement in the string declaration, if it is a simple query.  PowerShell's Get-Content mechanism makes reading a file very easy.  Also, clean up after yourself, I won't include that here.

UPDATE:  I have posted a full script to export to Excel or XML in a followup post.