Example for http://stackoverflow.com/questions/15382535/how-do-i-return-the-default-record-type-for-an-object-for-any-given-user

Admin.profile

<?xml version="1.0" encoding="UTF-8"?>
<Profile xmlns="http://soap.sforce.com/2006/04/metadata">
    <recordTypeVisibilities>
        <default>true</default>
        <personAccountDefault>true</personAccountDefault>
        <recordType>MyObject__c.A</recordType>
        <visible>true</visible>
    </recordTypeVisibilities>
    <recordTypeVisibilities>
        <default>false</default>
        <recordType>MyObject__c.B</recordType>
        <visible>true</visible>
    </recordTypeVisibilities>
    <userLicense>Salesforce</userLicense>
</Profile>

package.xml

<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
    <fullName>boxrt</fullName>
    <types>
        <members>Admin</members>
        <members>Standard</members>
        <name>Profile</name>
    </types>
    <types>
        <members>MyObject__c.A</members>
        <members>MyObject__c.B</members>
        <name>RecordType</name>
    </types>
    <version>27.0</version>
</Package>

Standard.profile

<?xml version="1.0" encoding="UTF-8"?>
<Profile xmlns="http://soap.sforce.com/2006/04/metadata">
    <recordTypeVisibilities>
        <default>false</default>
        <personAccountDefault>true</personAccountDefault>
        <recordType>MyObject__c.A</recordType>
        <visible>true</visible>
    </recordTypeVisibilities>
    <recordTypeVisibilities>
        <default>true</default>
        <recordType>MyObject__c.B</recordType>
        <visible>true</visible>
    </recordTypeVisibilities>
    <userLicense>Salesforce</userLicense>
</Profile>