If your Google Sitemap file is in "pending" status and you are worried that it will never come out of that status, I would not worry. Google recently posted an announcement that this is a known issue and they are working to resolve it.
The announcement was posted by Google's JohnMu:
Some new Sitemaps submitted via Webmaster Tools may remain in a "pending" state. We are aware of this issue and are looking into it; you do not need to take any action. This will have no effect on your site's performance in search results.
We have some worried webmasters, who I have notified not to worry. There are threads on this topic at WebmasterWorld and Google Webmaster Help, amongst others.
Like I said yesterday, Google Webmaster Tools is buggy, so don't let the bugs, um... bug you out (sorry, I had to).
Forum discussion at WebmasterWorld and Google Webmaster Help.

Comments:
Rob Abdul
02/20/2009 09:14 am
Wow, amazing – I’ve had the pending status on many of my sitemaps. I knew if there was any place it would be discussed; it would be here on seroundtable.com.
Rob Abdul
02/21/2009 01:00 pm
Just to let you know the audience know about 10 hours ago, all my sites are indicating that the sitemaps have been downloaded.
Spiffyguy
02/15/2011 04:17 am
I've tried contacting to see if this issue would resolve already. It has not. Something about an invalid command.. Thanks
Discontinued
08/28/2011 07:45 pm
This will have no effect on your site's performance in search results. LOL!!!!