rocknbil - 6:27 pm on Jul 16, 2010 (gmt 0)
You bill for your time, period, make it perfectly clear that this is time you should be working and you are billing for the phone conversation. They won't like it, but the customers you value won't mind a bit.
As for the updates, maintaining long time clients, even small ones, is always a good thing. There is always the potential they will shoot you a lead or talk about you. I suggest maintaining a running bill and when it gets to a billable point, bill them for it. I have some clients that take a month or two to hit with a bill for $50.
If they're still too much of an annoyance, farm it out, there are millions of developers who will take these small time annoying jobs and develop them into quality business relationships.