I'd be surprised if it has not filled up yet. Usually, the H1-B cap gets filled weeks after the start of the U.S. Fiscal Year (October). If by any chance you intend to work in a non-profit or academic organization, then you should not worry about the issue: there is no cap for these types of employers. Check out this website:
http://www.usavisanow.com/h1bnewsquota.htmlAccording to them, the quota for FY 2007 was reached on July 2006, even before the period started. So for the next FY, it would be recommended to file as soon as possible. If we extrapolate from last year's experience, you may be able to apply for FY 2008 on the fourth week of April. Hope this helps