blogapi.module: Blog ID and Validate For New Posts

Posting with MarsEdit, validation is failing in blogapi.module for new posts in RC4 because of the blog ID (see below). Prior versions would map a blog ID of "1" to a content type of "blog". In RC4 the blogapi module is treating the blog ID as synonymous with content type on new posts. Updates to existing posts are unaffected and work correctly. Changing the blog ID to "blog" in MarsEdit works around this issue. Is this by design or a bug?

Request text:
<?xml version="1.0" encoding="utf-8"?>
<methodCall>
<methodName>metaWeblog.newPost</methodName>
<params>
<param>
<value><string>1</string></value>
</param>
<param>
<value><string>[user]</string></value>
</param>
<param>
<value><string>[password]</string></value>
</param>
<param>
<value>
<struct>
<member>
<name>mt_allow_comments</name>
<value><int>1</int></value>
</member>
<member>
<name>mt_tags</name>
<value><string></string></value>
</member>
<member>
<name>mt_keywords</name>
<value><string></string></value>
</member>
<member>
<name>mt_convert_breaks</name>
<value><string>0</string></value>
</member>
<member>
<name>title</name>
<value><string>foo</string></value>
</member>
<member>
<name>mt_excerpt</name>
<value><string></string></value>
</member>
<member>
<name>description</name>
<value><string>foo</string></value>
</member>
<member>
<name>mt_text_more</name>
<value><string></string></value>
</member>
<member>
<name>mt_allow_pings</name>
<value><string>1</string></value>
</member>
</struct>
</value>
</param>
<param>
<value><boolean>0</boolean></value>
</param>
</params>
</methodCall>

Response text:
<?xml version="1.0"?>
<methodResponse>
<fault>
<value>
<struct>
<member>
<name>faultCode</name>
<value><int>1</int></value>
</member>
<member>
<name>faultString</name>
<value><string>Blog API module is not configured to support the 1 content type, or you don't have sufficient permissions to post this type of content.</string></value>
</member>
</struct>
</value>
</fault>
</methodResponse>