Based on Google queries, e-learning (about 200,000,000 results) takes the cake over elearning (about 14,400,000 results) in 2007. So the world seems to like the hyphen.My results are a little different but there certainly are more pages out there that have the hypen.
However, I actually believe the trend is more to drop the hypen. To back me up I went to Google Trends to see what the trend is for people searching. Here's what I saw:
"eLearning" has almost caught "e-Learning" in terms of what people use in their searches.
In the United States -
"eLearning" is used more often in searches than "e-Learning" ...
Bottom line, like Gabe mentioned e-mail got shortened to email, I would be surprised if eLearning doesn't become the term of choice.