@sbarker - The whole point of like-kind exchanges is to treat business transactions that are basically swapping similar business property in a fashion that is generally nontaxable (just merely realized, not recognized). However, there are certain situations where a like-kind exchange is taxable (recognized gain); this occurs when boot is received.
So, if you have a realized gain (FMV property received - basis of prop. given up) the only portion of that realized gain that would be recognized (taxable) is up to the amount of boot received.
10,000 FMV property received
(5,000) basis of property given up
= 5,000 realized gain (if 0 boot, then 0 recognized)
However, if there is 2,000 boot received, then 2,000 is recognized gain.
This may be overly-simplified, but I think it's important to be straight on the terminology. If you don't have the ninja notes for REG I would highly recommend them. Jeff has a good break-down of like-kind exchanges in there that is easy to understand and shows the different variables that you could see on the exam.
FAR - 81 (8/31/12)
AUD - 93 (10/19/12)
BEC - 79 (11/27/12)
REG - 92 (2/8/13) DONE! All 1st attempt!