I don't think you will see APDL for the iPhone anytime soon. ADPL always depended on the easy uploading/downloading of data (over a sync conduit) that Palms/WM provided to really make it work well.
Yes it works very well on my Palm.
Additionally, I THINK the last time I looked at APDL, they had discontinued use of stand alone programs for importing your schedules to a web-based system (meaning you can to be online to use it), and you HAD to use Logbook Pro to get your data out of APDL, which meant that you had to buy LBP if you were going to use the data in any way (someone correct me if I'm wrong on this).
I have both and they work together like a champ with a few exceptions. Major problem is tech support.
It's really too bad, because nothing worked as well as APDL for doing what it does....keep your times and check for legalities. All the other logbook programs for the iPhone either try to be all things to all pilots (GA, Corporate, etc) or are filled with bloat to the point they're almost unusable.
Could not agree more..
Now the last time I talked with the Flightline people, they SAID they were working on an iPhone app. No dates were given, but they said it was "in testing".
I look forward to see that.
You could even set it up to scan for open time, do swaps or other PCS transactions, check the reserve list, and whatever else your little heart desired.
Awesome, awesome, awesome, awesome, no I got a big heart. 
Just my opinion...
Nu