Hi lmattox,
Sure. It's possible now.
In your feed's ListDataSource tag, add a Parameter to grab the URL param value. Example:
<xmod:Feed>
<ListDataSource CommandText="SELECT * FROM Companies WHERE CompanyId=@cid">
<Parameter Name="cid" Value='[[Url:cid]]' DataType="Int32" />
</ListDataSource>
...
</xmod:Feed>
It is good practice to specify the DataType for parameters - especially those that can be user-supplied. So, in this case you're ensuring the passed-in value is a number. This helps prevent scripting attacks.
Best,
Kelly