A Google News publisher asked in a Google News Help thread why his publication rarely comes up in the Google News alerts for specific queries he subscribed to. Inbal from Google explained how alerts get sent and how you need to rank in Google News to be included.
Inbal said:
In order to be included in Google News Alerts, an article must be included in Google News and appear in the top ten results of Google News for specific search terms.
Clearly, the first part of the answer is obvious. To be in Google News Alerts, you must first be indexed by Google News. The second part is less obvious for many publishers, but for SEO's it likely makes a lot of sense. You must be in the top ten results at the time the alert is triggered (both RSS and Email) for you to show up in Google News Alerts. I believe the frequency of your alerts makes a difference, because the Google News rankings often change throughout the day.
Forum discussion at Google News Help.

Comments:
Tony Sulon
08/28/2009 10:58 am
A friend of mine who is a relatively well known dating coach called Jonathan Sankey (aka T from www.seduceinseconds.com) got into google news for "attracting women". The thing is that this term was not generally used for the dating industry, it was usually used for other businesses so he didn't come up at all in google as it looked highly irrelevant.