<p>I am writing a custom maven2 MOJO. I need to access the runtime configuration of another plugin, from this MOJO.</p>

<p>What is the best way to do this?</p>

I'm not sure how you would do that exactly, but it seems to me that this might not be the best design decision.  If at all possible you should aim to decouple your Mojo from any other plugins out there.
Instead I would recommend using custom properties to factor out any duplication in the configuration of separate plugins.
You can set a custom property "foo" in your pom by using the properties section:
```
```
<project>
  ...
  <properties>
    <foo>value</foo>
  </properties>
  ...
</project>
```
```
The property foo is now accessible anywhere in the pom by using the dollar sign + curly brace notation:
```
```
<somePluginProperty>${foo}</somePluginProperty>
```
```