Nest additional shortcodes in `[switch]`

After having a conversation with [Christopher Cool](http://www.christophercool.com), he is doing some really "cool" stuff with the `[switch]` shortcode.

The next level is using other shortcodes inside of a switch. This goes against the native WordPress shortcode functionality, so this may lend into starting a new shortcode displaying or hiding a content block based on `$_REQUEST` variables.

My initial thoughts are calling it **block**. The possible use is:
```
[block field="field1" value="show"]
    Hello there [as what="firstname"]! How are you today?
[/block]
```

A limitation I see initially is nesting blocks
```
[block field="field1" value="show"]
    [block field="field2" value="on"]
        Field 1 is showing and Field 2 is on.
    [/block]
    [block field="field2" value="off"]
        Field 1 is showing and Field 2 is off.
    [/block]
[/block]
```

This is probably a stand-alone issue, but still something to consider. Is the idea useful to have "advanced" control? `if field1=show AND field2=on` 

Also, is *block* a good name? Any other ideas?