The bit about Thanksgiving is basically accurate - I contacted them at 15:52 Pacific time (23:52 GMT) on Friday the 23rd of November, saying that I'd take further action if things hadn't been fixed by close of business on the following Friday (the 30th). While I'm happy to accept that this might have cost them Friday and Monday (if the MPAA are the sort to offer a 5 day long weekend), that's still 4 business days of response time. I telephoned them on Friday morning (around 10AM Pacific time) and was told I'd get a call back shortly. By Saturday it seemed likely that this wasn't going to happen, so emailed the ISP. At 19:13 Pacific time on Saturday, I received an email from the ISP informing me that they were going to contact Paul Egge at the MPAA. There was an ISO available from the MPAA site until at least 09:22 Pacific time (17:22 GMT) on Monday the 3rd of December, which had been removed by 23:00 or so GMT (the next time I checked).
So, to summarise. The infringing material was still available the best part of 9 days after the original notification was sent. At least 4 of those 9 were business days. The material was not removed until after I had contacted the ISP and they had informed me they were going to contact the MPAA. Further interpretation is left to the reader.