Is it proper to ask geographically based career questions? For example, "What US city has the greatest opportunity for software engineers?"
Typically no, as these would be too localized:
This question would only be relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet.
There can be exceptions, for example, on a poker site questions about Las Vegas would certainly be relevant, yes?
The rule of thumb is to generalize the question so it is relevant and helpful to as many people in your community as possible -- don't give someone a fish, teach them how to fish, etc.
If it's likely to still be valuable in a year, eg. what user groups are there in the Houston area then yes.
If it's geographically and time limited, eg. is Initrode in Houston hiring, then no