It all depends on how you’re using MySQL. If I develop an application that uses MySQL, I don’t believe that I can include MySQL (say on a CD) and sell it - not without a license fee from MySQL. But I could have that same app make use of a MySQL databases that I was hosting for people who bought the app and it would be fine. At least that’s what I understood from the email I received from MySQL a long time back. 
@FlasFish – never feel bad about going to a client with a bit of bad news about their current set up. Especially if it wasn’t you who recommended the set up in the first place. The best you can do is give them all the options available to them and let them make the call.
The only time to feel bad is when something you recommened causes the problem. Then… well usually cutting them a deal works in making them happy again.
