iPhone 4 32GB-4GB Discrepancy between iTunes and iPhone on free space

Also, Ive tried resetting and restoring the phone as well as restarting my computer to see if theres any issue there. As far as I can tell, Im just simply missing 4GB of space on my phone.
MBP 2.24GHz IC2 13.3" 4GB RAM Mac OS X (10.6.7) 32 GB iPhone 4 (GSM) iOS 4.3.1

There is an ongoing issue. It is in iTunes, not your phone. The amount of space is being essentially misreprsented by by iTunes and there are several threads on the topic. Hopefully and upcoming update to iTunes will resolve it.
Custom PC 6GB RAM / Nvidia 280GTX Graphics/ 3.5TB HD Windows XP Pro iPad1-iPad2 64Gs-iPhone4-AppleTVx2-iTouch 4G

Interesting. I didnt find any threads on this in the forums (but then again, I didnt look terribly hard).
My concern is that the amount of music that I have on my phone is 21.5GB or so, the space for apps is around 3.6GB, and I have no photos, movies, or other items (aside from less than ~.5GB of PDFs/books on iBooks). How is it that 21.5+3.6+1 = 26.1 and I should have 29.1 available on the phone?*
Also, how is it that the same amount of music fit on the 32GB iPhone 3GS, but not on the iPhone 4?
*After deleting some music, its down to 23.9GB vs. the 29.1GB that should exist, thus the 4GB missing space (along with the free 1.2GB I mentioned above).
MBP 2.24GHz IC2 13.3" 4GB RAM Mac OS X (10.6.7) 32 GB iPhone 4 (GSM) iOS 4.3.1