I don't get the best reception on my iPhone at home. At best I get 2 bars and mostly 1 bar. I purchased the iPhone dock this weekend and noticed that when docked I now have 4 bars! Why would the dock result in better reception?
Most likely it has nothing to do with the dock. Over the past few weeks, I have watched my signal strength improve drastically in areas I was lucky to get 1 -2 bars edge. Now I show 3-4 bars 3G. It's part of AT&T's network update.
This is believable. The dock could simply be working as an extension of the antenna (not intentionally). The location and properties of items near an antenna can and do affect its performance.
So let's say that for some reason the dock is acting like an antenna of sorts--again, not intentionally but due to its positioning, wires connected to it, etc. So it receives this RF energy but has no receiver with which to use it. So that energy is re-released (scatter) and then captured by the nearby iPhone antenna, ending up with an iPhone with better reception.
Or the whole thing could be a figment in the mind of the OP. (JK!)