The Federal Election Committee gave the Associated Press a list of overseas donors that did not fill their state designation blank on October 6,2008.  Only US citizens living abroad can make campaign donations.  According to FEC records Obama raised $3.3 million from donors who did not list their home state or used an abbreviation that didn't match any of the 50 states or US territories.  The $3.3 million list does not include donations under $200 and do not have to be itemized. Obama's campaign does not identify these donors; unlike Mc Cain who lists all of his donors on his web site.
The Republican National Committee filed a complaint with the FEC on 10/06/2008 asking for an investigation of Obama's overseas money.
Now Obama's staff requests passport number from overseas donors,
Most donors give in even dollar amounts.  Ken Boehm, head of the National Legal and Policy Center, says they are converting local money into US dollars.
"I have never seen this in all my years (30) of raising money for political candidates.  The first thing it suggests is foreign currency transactions-contributions from foreign donors which is clearly illegal," said Boehm.
One possible source of these ill funds is the Obama online store which sell t-shirts and other items.  Newsmax among others showed that Palastinians from Gaza and other foreigners had made large buys online.  Newsmax claims to have "virtually shut down" the online store, but a quick Google search finds a bunch of these sites (including offical ones) are active now.