partner-contact/partner_firstname/partner_view.xml

<openerp>
  <data>
    <record id="view_partner_simple_form_firstname" model="ir.ui.view">
      <field name="name">res.partner.simplified.form.firstname</field>
      <field name="model">res.partner</field>
      <field name="inherit_id" ref="base.view_partner_simple_form"/>
      <field name="arch" type="xml">
        <field name="category_id" position="before">
          <group>
            <field name="lastname"/>
            <field name="firstname"/>
          </group>
        </field>
      </field>
    </record>

    <record id="view_partner_form_firstname" model="ir.ui.view">
      <field name="name">res.partner.form.firstname</field>
      <field name="model">res.partner</field>
      <field name="inherit_id" ref="base.view_partner_form"/>
      <field name="arch" type="xml">
        <field name="category_id" position="before">
          <group>
            <field name="lastname"/>
            <field name="firstname"/>
          </group>
        </field>
      </field>
    </record>

  </data>
</openerp>