How to wrap text around an image using HTML/CSS

Question

you have to float your image container as follows:

HTML

<div id="container">
    <div id="floated">...some other random text</div>
    ...
    some random text
    ...
</div>

CSS

#container{
    width: 400px;
    background: yellow;
}
#floated{
    float: left;
    width: 150px;
    background: red;
}

FIDDLE

http://jsfiddle.net/kYDgL/

With CSS Shapes you can go one step further than just float text around a rectangular image.

You can actually wrap text such that it takes the shape of the edge of the image or polygon that you are wrapping it around.

DEMO FIDDLE (Currently working on webkit - caniuse)

.oval {
  width: 400px;
  height: 250px;
  color: #111;
  border-radius: 50%;
  text-align: center;
  font-size: 90px;
  float: left;
  shape-outside: ellipse();
  padding: 10px;
  background-color: MediumPurple;
  background-clip: content-box;
}
span {
  padding-top: 70px;
  display: inline-block;
}

<div class="oval"><span>PHP</span>
</div>
<p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has
  survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing
  software like Aldus PageMaker including versions of Lorem Ipsum.Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley
  of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing
  Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy
  text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised
  in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>

Also, here is a good list apart article on CSS Shapes

Addition to BeNdErR's answer:
The "other TEXT" element should have float:none, like:

    <div style="width:100%;">
        <div style="float:left;width:30%; background:red;">...something something something  random text</div>
        <div style="float:none; background:yellow;"> text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text  </div>
    </div>

If the image size is variable or the design is responsive, in addition to wrapping the text, you can set a min width for the paragraph to avoid it to become too narrow.
Give an invisible CSS pseudo-element with the desired minimum paragraph width. If there isn't enough space to fit this pseudo-element, then it will be pushed down underneath the image, taking the paragraph with it.

#container:before {
  content: ' ';
  display: table;
  width: 10em;    /* Min width required */
}
#floated{
    float: left;
    width: 150px;
    background: red;
}