The things to note in that graph are the general overall decline of sales in September and subsequent peak over the last week. In their conference call, Apple noted that sales of the iPhone at the end of the quarter were much slower due to rumors of the new phone. This seems to fit very well with the above data, as well as anecdotal evidence from quite a few other devs I've talked to.
The recent peak is just slightly higher than the peak in July, and it isn't based on having a new app in the new release list. That is very encouraging to me as a dev. While I expect the last few days to continue to be a "peak" at least in the short term, I think the new normal will be well above the old levels. I hope/expect to continue the upward trend that was broken at the beginning of September as I continue to improve my apps, and now thankfully as Apple has gotten back to selling a lot of iPhones.
Another thing this chart tells me is that I need to get some apps out for Android as well. The trough from lower iPhone sales probably would have been filled by sales of Android phones during that time period. I am currently working on an Android version of my budgeting app, so once that comes out I'll be sure to do a comparison post.
If you've read this far and are interested in the mobile app market you may want to check out my newsletter. It's periodic emails (no more than 1-2 a month) on mobile app sales and the different markets.