No mobile operating system in the U.S. has won the hearts of developers, who are cautiously moving forward by porting their applications to all six major operating systems, according to ChubbyBrain, which tracks VC activity. To find out which of the six major U.S. operating systems (Android, iPhone, Palm (NSDQ: PALM), RIM (NSDQ: RIMM), Symbian and Windows) had a lead, ChubbyBrain analyzed all mobile VC deals in 2009 totaling more than $400 million (Updated to correct dollar figure).

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Here’s the results:

Multiple OS: Of the 17 companies, 67 percent said they were developing their applications for multiple operating systems, and of those, three-fourths said they were developing for all six.

Single OS: Of all the companies, 33 percent said they were developing for a single platform. Of those companies, nearly half, or 49 percent, said they were building only iPhone apps. After that, it was RIM (20 percent); Windows (15 percent); Android (8 percent); Symbian (5 percent); and Palm (3 percent).