I have resolution to the BT Keyboard pairing problem now. So this is really a solution posting. Sorry if dup's some other info posted else where on the Mac (but honestly I didn't buy the Mac to then have to search hours on forums to have it work for me). However, upon unboxing the Mac Mini (with i7 2.3 GHz CPU), and then initially booting for OS X setup, I could not get my Apple Wireless Keyboard (2009 model) to pair with the Mac Mini. I tried everything possible on the keyboard side, power-on, power-off, pressing right hand side button. On the OS side, for setup mode, their nothing you can do, with exception of typing the security code and hitting the return key, where the Mini thinks about the code you entered with spinning sprite for about 2 minutes, and then it puts the same code back up again for you to repeat the process, and your in an endless loop. I could not make keyboard pair with the Mini for this OS X setup phase.
After the above frustration with this problem, I finally pulled a USB keyboard from a PC, and plugged it into the Mac Mini, just to get me through the OsX setup on the Mini. THEN, after taking the firmware update for Mini, as part of the OsX software updates, the BT pairing with wireless keyboard worked flawlessly with no problem. (yes, paired as quickly/easily as how you'd expect most Apple products to perform).
My conclusion is that 1 of 2 possibilities exist (where without more research to the problem and loss of my time, and apple not paying me to QA):
1. Apple has some problems with their BT pairing process on the Mini with Apple Wireless Keyboard (2009 for sure, maybe others I don't know), where these problems don't exist once the OS X fully booted and you attempt the pairing of the keyboard.
2. Apple's firmware update, taken via the regular OS X software update channel, for the Mac Mini (i7 2.3 GHz) provides some fix to the Blue Tooth pairing process for the Apple Wireless Keyboard (2009 model).
I hope this may save some new Mac Mini owner a bit of time, if they 1st choose to hook BT keyboard after the Mini's unboxing.