Despite the comments in this thread, I continue to experience exactly the same problem (1113: unknown method name null).  My client is in Java (can I cross-post this to the Java boards?); I used Axis 1.1 final to generate stubs against the sforce20.wsdl.  From the generated SfconnectorLocator.java:

private final java.lang.String SalesforceConnector_address = "https://www.salesforce.com/servlet/servlet.SoapApi";

So...the address looks right.

Request message:

<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
 <soapenv:Body>
  <ns1:login soapenv:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:ns1="sfconnector:SalesforceConnector">
   <version xsi:type="xsd:string">2.0</version>
   <username xsi:type="xsd:string">USERNAME</username>
   <password xsi:type="xsd:string">PASSWORD</password>
   <secure xsi:type="xsd:boolean">true</secure>
   <remoteApplication xsi:type="xsd:string"></remoteApplication>
  </ns1:login>
 </soapenv:Body>
</soapenv:Envelope>

Any thoughts on what the issue might be?

Help!!!

My Java code no longer functions correctly, or rather no longer returns successful results. I'm querying to determine if a lead already exists. The code hasn't changed in a couple of weeks, assumming the API chage might be the culprit. My query request dump looks like this:

Request->
<?xml version="1.0" encoding="UTF-8"?>
<soap-env:Envelope xmlns:soap-env="http://schemas.xmlsoap.org/soap/envelope/" xm
lns:tns="salesforce" xmlns:types="salesforce/encodedTypes" xmlns:xsd="http://www
.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" so
ap-env:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
 <soap-env:Header>
  <headerStruct>
   <version type="string">1.9</version>
   <session_id type="string">R9aOZgwrWl5i0PY36o.3JFIrDJDj_dy6NvHz96Bgw_fLgpkl62C
ZrfXUjGE2lQsP.36b7mOoCg5OIizEGqIvEPbtzKggVlhL</session_id>
  </headerStruct>
 </soap-env:Header>
 <soap-env:Body>
  <tns:query xmlns:tns="sfconnector:SalesforceConnector" type="methodCall">
   <type type="string">lead</type>
   <maxRows type="int">1</maxRows>
  </tns:query>
  <select type="array">
   <field type="string">id</field>
  </select>
  <filter type="array">
   <item type="map">
    <field type="string">email</field>
    <value type="string">joe@joe.com</value>
    <operator type="string">contains</operator>
   </item>
  </filter>
 </soap-env:Body>
</soap-env:Envelope>

Response->
<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:soap
enc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:tns="salesforce" xmlns:typ
es="salesforce/encodedTypes" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instanc
e" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
 <soap:Header/>
 <soap:Body>
  <soap:Fault>
   <faultcode>1100</faultcode>
   <faultstring>select list not specified in query</faultstring>
  </soap:Fault>
 </soap:Body>
</soap:Envelope>