It's worth noting this part of the email. There have been conflicting reports as to whether a reservation means that a phone will be there for you regardless of when you come in on the 24th.
A couple things to note:
- It says your "reservation" will be held, not your "phone". I'm not sure if this is suggesting that hardware will not necessarily be held, just worth noting.
- The bottom of the email still says "Pre-authorization does not guarantee iPhone availability at an Apple Retail Store. iPhone is sold on a first-come, first-served basis." I think "Pre-authorization" is not the same as a reservation. If you remember, the original iPhone had so many problems with activation at launch that when the 3G came out, Apple and AT&T allowed for "pre-authorization" which would streamline the process. It seems more likely that this is what they are referring to.
So, I still have no idea whether this means phones will be held for those with reservations or not. When I called my local Apple Store, they seemed to suggest that an actual phone will be held until the end of the business day for those with reservations.
I'm not going to trust that though. I plan on getting to the store before they open, and will get in the reservation line. I can't afford to not get on Thursday as I have to get my 3GS back to Gazelle within the 30 day lock-in period, or I'm out at least $82. I had a pre-order that was cancelled by Apple... bastards.
Edit: Removed email image as someone already posted it.