Q:

TextView failing hard to alignTop and alignBottom

The "sun is red" should align to the top of the image, and "2pm" should align to the bottom. Why don't attributes layout_alignTop and layout_alignBottom work as documented?
  <RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="9dp">
        <ui.RoundedImageView
        android:id="@+id/img_user"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginRight="9dp"
        st:cornerRadius="3"
        android:background="@drawable/black_rounded3" />
        <TextView
                android:id="@+id/uname"
                android:layout_toRightOf="@id/img_user"
                android:layout_alignTop="@id/img_user"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textColor="#000000"
                android:textStyle="bold" />
        <TextView
                android:id="@+id/time"
                android:layout_toRightOf="@id/img_user"
                android:layout_alignBottom="@id/img_user"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textColor="#909191" />

        <LinearLayout
                android:id="@+id/layout_g"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginRight="9dp"
                android:layout_marginLeft="9dp"
                android:layout_alignParentRight="true"
                android:clickable="true"
                android:gravity="right">
                <TextView
                        android:gravity="right"
                        android:layout_gravity="right"
                        android:id="@+id/gtext"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        style="@style/text_detail" />
        </LinearLayout>
      </RelativeLayout>

A:

Why don't attributes layout_alignTop and layout_alignBottom work as documented?

-> They do.
The problem is with the RoundedImageView object you're using. My guess is that it is onMeasure is not correct and is not returning proper value for where the top and bottom of itself is. With out knowing anything else about this RoundedImageView that you're using I can't really point you in a direction to get it fixed.
I changed your code to this:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="9dp">
    <ImageView
    android:id="@+id/img_user"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginRight="9dp"

    android:background="@drawable/black" />
    <TextView
            android:id="@+id/uname"
            android:layout_toRightOf="@id/img_user"
            android:layout_alignTop="@id/img_user"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="#000000"
            android:text="the sun is red"
            android:textStyle="bold" />
    <TextView
            android:id="@+id/time"
            android:layout_toRightOf="@id/img_user"
            android:text="2pm"
            android:layout_alignBottom="@id/img_user"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="#909191" />

    <LinearLayout
            android:id="@+id/layout_g"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="9dp"
            android:layout_marginLeft="9dp"
            android:layout_alignParentRight="true"
            android:clickable="true"
            android:gravity="right">
            <TextView
                    android:gravity="right"
                    android:layout_gravity="right"
                    android:id="@+id/gtext"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    />
    </LinearLayout>
  </RelativeLayout>

And it properly aligns the text. Here is screenshot:

