are you getting any links to the deep product pages?
without those deep links you will probably see yourself hovering around the ~10% of sites in index since that is what google seems to be crawling and finding regularly on your site. Especially if your internal linking was suboptimal pre July '09.
Make sure that google can crawl, and re-crawl, all the pages you want to be found in the index. Link to, and interlink, your product pages well.
Build links to the product pages.
This should help increase the number of your pages found in the index.