A word meaning "those who are plugged in"?

Solution 1:

The Illuminati is a nice term that describes a community of people with a special/secret knowledge. (Unfortunately, it has been somewhat soiled in recent times by conspiracy theorists and is now most commonly used to label a supposed 'secret society' controlling world governments/media/etc.)

Enlightened comes from the same root and describes people endowed with a certain knowledge/understanding. This word often appears in religious context but by no means is it limited to that.

A person with esoteric knowledge is someone who knows/understands something which only a select few know/understand. Here, rather than being members of a secret society, the 'select few' are simply those who have studied the topic in question.

The Intelligentsia is a term used to refer to intellectuals of a high social class involved in cultural/educational development, creative labour.

If we remove that sense of special/privileged, I suppose any of the following could also work, depending on your specific context:

Nouns: Contributor; Member; Scholar; Academia;

Adjectives: Learned; Erudite;

Most of these latter words tend to relate to either knowledge or connectedness, rather than both. A dictionary should help you with their specific uses.

Hope that helps.

Solution 2:

Such folks are in the know or in the loop:

in the loop
aware of information known only to a privileged few^NOAD

An appropriate single word would be the group noun, the initiated:

the initiated
a small group of people who share obscure knowledge^NOAD

Solution 3:

A contemporary version is wired, in the sense of connected.