The California senate seat is currently held by Senator Barbara Boxer, who's had the job since 1992 and is up for re-election. Boxer is considered the more liberal of California's two Democratic senators.
Fiorina served as the "Chair of Victory" for the Republican National Committee during the 2008 presidential election.
During the election, she was considered a potential candidate for a vice presidential nomination before Alaska Governor Sarah Palin was given the nod by Senator John McCain's campaign.
California Assemblyman Chuck DeVore, R-Irvine, has already announce his campaign. There is speculation that Gov. Arnold Schwarzenegger might also choose to run, though he has denied any intention.
Public opinion polls taken in February and March show a siginicant lead by Boxer in a matchup against Fiorina.
Fiorina has taken on the issue of executive compensation in the wake of Wall Street's meltdown, an interesting tactical choice since she was given $45 million after stepping down from HP.
Jackson West wonders if this means Fiorina will suddenly decide to hate on the gays like Meg Whitman has.