The team behind Amazon SimpleDB is in the process of designing and implementing a new API call. The new call will return information about a particular SimpleDB domain. They have posted the design spec to the SimpleDB forum and would be very interested in receiving some more feedback.
I've said it before and I'll say it again -- much of what we do at Amazon is driven by real feedback from real customers. If you are using or are thinking about using SimpleDB, please take a look at the spec and let us know (via a post to the forum) what you think.