Split your Magento sitemap into smaller chunks
We deal with large scale e-commerce stores on a daily basis and a recent fix we had to implement was to allow the sitemap generated to be created in smaller chunks - so not to breach the 50,000 URL or 10MB limitation placed by Google Webmaster tools.
We have packaged up this little extension for you and popped it over on Magento connect. The extension is still pending at the moment, but we'll update the link once it is live:
Download Sonassi_SitemapChunk »