I recently received an email from a former co-worker. She was curious to know what I read/do to know what it is "trending" in the software world. I think this is good knowledge to share, and I'm also interested in what others do to keep up. Here's my response to her:
My technique for staying up-to-date is mostly reading, and attending some user group meetings. For reading, I read news.ycombinator.com, as well as infoq.com - who I now write for. DZone.com (esp. Javalobby and its HTML5 Zone) is also pretty good, as is arstechnica.com. I don't read nearly as much as I used to when I was subscribed to all of their RSS feeds and read them religiously.
Nowadays, most of my information comes from Twitter. I follow people that are involved in technologies I'm interested in. I try to keep the number of people I follow to 50 as I don't want to spend too much time reading tweets.
For meetups, most are on meetup.com these days. I'd find a couple that have technologies you're interested in (e.g. a local HTML5 meetup or Java user group) and join the group. You'll get email notifications when they have meetings.
Other than that, sometimes I do "conference driven learning". I'll pick a few technologies I'm interested in learning, submit a talk to a conference or user group, then be forced to learn and present on them when it gets accepted. It can be stressful, but it works and usually results in a good presentation because I can share the experience of learning.
One interesting thing I've realized about Twitter is I can make technologies seem "hot" based on the people I follow. If I'm following a bunch of AngularJS folks, my feed is filled with Angular-related tweets and it seems like the hottest technology ever. If I tweak who I follow to have a bunch of Groovy enthusiasts, or Scala folks, the same thing happens.
Of course, the best way to learn new technologies is to use them in your daily job. I strive to do this with my clients, but it doesn't always work out. I've found that working on open source projects and speaking at conferences can help you learn if you're in a stagnant environment. Then again, if you're not happy at work, quit.
What do you do to stay on top of emerging trends in technology?