What's the deal with stealth?

I’ve seen a number of articles of late in which the journalist refers to a company having been in “stealth” mode. Here’s an example:

Apptio, a startup partly funded by Netscape co-founder Marc Andreessen, came out of stealth mode Monday to push its SaaS (software-as-a-service) offering meant to help IT shops track exactly how much their assets cost the business. More of this article at:
http://cwflyris.computerworld.com/t/3280998/121940157/118824/0/


Does creating the perception of a company being stealth heighten interest in a start-up to support a corporate launch campaign?