I was dealing with this as well. The WooTumblog plugin came along before WordPress version 3.1 with post formats was released. It then used custom taxonomies, but now has the option to utilize post formats instead. Besides the cool dashboard widget all it really does is adds custom fields and provides code snippets to add to your template files. Since Twenty Eleven provides separate templates for each post format it seems foolish to use WooTumblog with it.
However, Post formats do not make much sense just yet. Using the same post editor fields for every post format and simply adding the appropriate content seems counter-intuitive to having this functionality at all. This really should be part of core where the post editor UI adapts, providing custom meta boxes for the selected post format. Then additional standardized template tags should be included in the codex for theme developers to adopt. Then we could all enjoy the true potential of post formats with portability (moving seamlessly between themes without losing custom post data.)