New York University's Brennan Center for Justice has been studying electronic voting systems and has concluded, not surprisingly, that they are vunerable to attack. It's not all bad news, though, as their report also concludes that the threat of interference with the voting process can be reduced by simple countermeasures, including random audits of paper records and a ban on wireless systems. You can find an executive summary of the report here.
The press release claims the report is the "first-ever systematic analysis of security vulnerabilities" in the three most common evoting systems used in the US, but that's just sales-speak probably by someone who doesn't realise that computer scientists like Avi Rubin, Ed Felten, Rebecca Mercuri, David Dill (a co-author of the Brennan report) and many others have been warning about the security problems with electronic voting for years. Rubin is publishing a book on the subject later this year and is and the director of ACCURATE, A Center for Correct, Usable, Reliable, Auditable, and Transparent Elections, funded by the National Science Foundation. Dill founded Verified Voting.
Update: HJ Affleck of FIPR points to a Washington Post story on the report.