I just ran into the same problem. I submitted the sitemap as well. Webmaster Tools found the feed and asked if I wanted to add it so I did as well. The errors it returned were:
Line 13
Status Invalid URL
This is not a valid URL. Please correct it and resubmit.
URL:
http://
Parent tag: channel
Tag: link
Problem detected on: Aug 22, 2009
Line 13
Status Incorrect namespace
Your Sitemap or Sitemap index file doesn't properly declare the namespace.
Parent tag: channel
Tag: link
Problem detected on: Aug 22, 2009
Line 13
Status Invalid XML attribute
The XML attribute of this tag was not recognized. Please fix it and resubmit.
Tag: link
Attribute: href
Problem detected on: Aug 22, 2009
Line 13
Status Invalid XML attribute
The XML attribute of this tag was not recognized. Please fix it and resubmit.
Tag: link
Attribute: rel
Problem detected on: Aug 22, 2009
Line 13
Status Invalid XML attribute
The XML attribute of this tag was not recognized. Please fix it and resubmit.
Tag: link
Attribute: type
Problem detected on: Aug 22, 2009
Line 14
Status Invalid XML: too many tags
Too many tags describing this tag. Please fix it and resubmit.
Parent tag: channel
Tag: link
Problem detected on: Aug 22, 2009
Line 34
Status Invalid XML: too many tags
Too many tags describing this tag. Please fix it and resubmit.
Parent tag: item
Tag: comments
Problem detected on: Aug 22, 2009
Line 54
Status Invalid XML: too many tags
Too many tags describing this tag. Please fix it and resubmit.
Parent tag: item
Tag: comments
Problem detected on: Aug 22, 2009
Line 79
Status Invalid XML: too many tags
Too many tags describing this tag. Please fix it and resubmit.
Parent tag: item
Tag: comments
Problem detected on: Aug 22, 2009