Yes but..
Twitter's response may not have been all that effective. But it's a helluva lot better than Web-2.0-alikes MySpace and Facebook who's attitude to this sort of thing is to pretend it isn't happening.
Multiple new versions of the Mikeyy cross-site scripting worm spread across the Twitter micro-blogging network over the weekend. The first in the latest batch of worms berated Twitter for poor security. Mikeyy Mooney, the VXer who got a job in security days after creating the first Twitter XSS worm over the Easter holiday …
You people don't understand, Twitter is a worthwile, exciting service, I'm sure if I didn't have a life of my own I'd want to borrow someone else's, or if I thought I was really, really, important and exciting then I could share my wonderful life with people who aren't as fun as me.
In the same vein, you can't expect them to consider things like XSS, after all this particular hack is really hard to exploit and has only been around 5 minutes..... ahem.