I got it! It turns out PyQt 4.5 was buggy, thus the error. I compiled the recently released 4.5.1 and it worked like a charm.
So about the script. It locked up when I posted a Tweet, but it did post to Twitter. I had to reopen the script to stop the hourglass from spinning. The thing it really lacks is a built-in timeline and functionality like @mention alerts and PM support. It's a nice start and I'd love to see it grow.