Companies typically release their earnings before the market opens, and then later host an analyst/investor conference call to discuss the results.

Here's a link to an interesting article abstract on the subject: Disclosure Rules For Earnings Releases And Calls | Bowne Digest. Excerpt:

In the aftermath of the Sarbanes-Oxley Act, the SEC changed regulations to bring quarterly earnings announcements in line with the generally heightened sensitivity to adequate disclosure. New regulations required that issuers file or furnish their earnings press releases on Form 8-K and conduct any related oral presentations promptly thereafter, to avoid a second 8-K. [...]

Sample from a news release by The Coca Cola Company:

ATLANTA, September 30, 2009 - The Coca-Cola Company will release third quarter and year-to-date 2009 financial results on Tuesday, October 20, before the stock market opens. The Company will host an investor conference call at 9:30 a.m. ( EDT ), on October 20. [...]

Sample from a news release by Apple, Inc.:

CUPERTINO, California—January 21, 2009—Apple® today announced financial results for its fiscal 2009 first quarter ended December 27, 2008. The Company posted record revenue of [...]

Apple will provide live streaming of its Q1 2009 financial results conference call utilizing QuickTime®, Apple’s standards-based technology for live and on-demand audio and video streaming. The live webcast will begin at [...]

the financial information is generally filed via SEDAR (Canada) or SEC (US) before the conference call with the investment community. This can take before either before the market opens or after the market closes. The information is generally distribute to the various newswire service and company website at the same time the filing is made with SEDAR/SEC.