Here's the script I use to generate tags for my Subtext posts. It writes the tag HTML to the screen and also copies it to the clipboard for immediate pasting:

if ($args.Length -ne 2)
{
  write-host 'Two arguments (site and tag list) expected'
  write-host 'Example: tags del.icio.us "scripts tags llama"'
  return
}

$site = $args[0]
$input = $args[1]
$delim = ' '
$splits = $input.Split($delim.ToCharArray())
$header = '<p class="tags">tags: '
$footer = '</p>'
$format = '<a href="http://' + $site + '/tag/{0}"'
$format += ' target="_blank" rel="tag">{0}</a> '

$html = new-object  System.Text.StringBuilder

[void]$html.Append($header)

for ($i = 0; $i -le $splits.Length; $i++)
{
  if ($splits[$i].Length -ge 1)
  {
    $newText = [System.String]::Format($format, $splits[$i])
    [void]$html.Append($newText)
  }
}

[void]$html.Append($footer)
set-clipboard -text $html
write-host $html

Example:

tags del.icio.us 'snow cookie alpaca'

... generates the following HTML:

<p class="tags">tags: 
<a href="http://del.icio.us/tag/snow" 
  target="_blank" rel="tag">snow</a> 
<a href="http://del.icio.us/tag/cookie" 
  target="_blank" rel="tag">cookie</a> 
<a href="http://del.icio.us/tag/alpaca" 
  target="_blank" rel="tag">alpaca</a> 
</p>

Have fun.

tags: