[dwringer]

I certainly can't speak in general but I noticed it enter my circles of friends when the World Poker Tour and Celebrity Poker Showdown games started on TV ~2003. Around that time it seemed like everyone I knew was suddenly interested in Texas Hold'em (before that I had basically only ever played 5-card draw).

[mk_stjames]

The movie "Rounders" came out in 1998... that was what did it for myself and my friend circle.