Running complex tasks in Phing can mean running out of memory, especially when altering or changing lots of files. I was recently working on a image sorting Phing project that sorted images based on EXIF information. The many thousands of files involved, along with the custom target used to extract the EXIF data caused the default available memory to run out quite quickly.
Context is a Drupal module that allows you to set up reactions that fire when certain conditions are met. This might be when a certain path is loaded, or when a particular content type page is viewed, or even on every page on a site. When the conditions are met a number of reactions can be fired, which include placing blocks, setting breadcrumbs, or just adding a class to the page template.
When you first install a Munin node it will try to install as many plugins as it can so that it can report on different things. For example, if you have a Varnish server running then Munin will detect this and enable the plugins so that it can report on the activity of Varnish. Once you have started getting data through to your Munin server then you can turn on plugins on the nodes to get more data.
When Munin does a data update it stores all of the data from the nodes as a set of rrd files. These files are then picked up by the munin-graph and munin-html programs and turned into the graph images and web pages that you are probably familiar with if you use Munin.