The Google Webmaster Central Blog announced improvements they have made to the robots.txt analysis tool.
The tool now recognizes all sitemap declarations and relative URLs. So now the tool will report the validity of all sitemaps URLs plus show data for relative URLs. In addition, Google has expanded the reporting to include data for not just the first problem encountered, like they did in the past. Now they also show all problems encountered, on multiple lines and itemized by line number.