Yes, there is wrong .info file

.info file contains extra information that should be added by the script which creates a Drupal package.

current content is:

; $Id: SEOChecklist.info,v 1.8 2009/02/19 14:04:47 sprydev Exp $
name = '"SEO" Checklist'
description = A Search Engine Optimization checklist for Drupal 6.

package = '"SEO" Checklist'
version = "6.8 Beta"
; Information added by drupal.org packaging script on 2007-11-20
version = "6.8"
project = "seo_checklist"
datestamp = "1195529707"
core="6.x"
; Information added by drupal.org packaging script on 2009-01-26
version = "6.x-1.0-beta2"
core = "6.x"
project = "seo_checklist"
datestamp = "1233006063"

And should be like that:

; $Id: SEOChecklist.info,v 1.8 2009/02/19 14:04:47 sprydev Exp $
name = SEO
description = A Search Engine Optimization checklist for Drupal 6.
core = 6.x

Fixed in 2.0.