I use wikidot.com and have many subdomains. It was easy to get indexed before. What I do was just digg it! then it will be indexed. But now the only page indexed is that of digg. The subdomains? nop. Possible solution? Thx.
bookmarking is good way, but google says that you must add site map for your site to webmaster tools to tell google bots about you site. so first add subdomain in webmaster tools as a new site and then verify it and then add site map for it. may be it will help you, good luck