Thousands turned out for a speech by Democratic Presidential nominee Barack Obama at Cashman Field on Wednesday.  In the speech, Obama focused on the economy and the recent plunge on Wall Street.  He said the problem is "too many in Washington and on Wall Street weren't minding the store," and called for tougher regulation of the market.  The Illinois senator also criticized Republican rival John McCain's claims as an agent of change.  Of McCain's pledge to take on the "old boy network" in Washington, Obama said, "In the McCain campaign, the old boy network is called a staff meeting."  Earlier in the day, Obama spoke to a crowd of about a thousand people in the Northern Nevada town of Elko, where he struck similar themes on the economy.  Meanwhile, Republican supporters of John McCain and Sarah Palin rallied in protest outside the event.  This was Obama's first visit to Las Vegas since late June, when he hosted a discussion on economic issues at UNLV.  His former opponent in the Democratic primary, Senator Hillary Clinton, campaigned for Obama in Henderson last month.