Regent - 5:48 pm on Oct 9, 2007 (gmt 0)

Yes, I'm noticing exactly the same thing. I receive the following XML response from search.yahooapis.com/SiteExplorerServices/V1/:

<Error xmlns="urn:yahoo:api">
The following errors were detected:
<Message>service temporarily unavailable [C:28]</Message>
</Error>

It seems the error is *only* with the API because when I try the same searches using the browser interface at siteexplorer.search.yahoo.com, everything seems normal and I receive more than 50 results.