Source:  U.S. Citizenship and Immigration Services, 4/1/11

U.S. businesses use the H-1B program to employ foreign workers in specialty occupations that require theoretical or technical expertise in specialized fields, such as scientists, engineers, or computer programmers.

USCIS starts accepting H-1B petitions subject to the fiscal year (FY) 2012 cap on April 1, 2011. Cases will be considered accepted on the date USCIS receives a properly filed petition for which the correct fee has been submitted; not the date that the petition is postmarked.
Read more about the H-1B Fiscal Year (FY) 2012 Cap Season.