There I was furiously developing software for a website using straight JDBC, which I had not used for a while, having worked with data abstraction layers and found a MySQL gotcha.
My dev version of MySQL had v5.0 and I was happily using subqueries and the likes. Then I uploaded the software to my hosting account at godaddy and voila all subqueries failed. After investigations, I figured out that godaddy were still in version 4.0 of MySQL (4.0.27) which does not support subqueries. Only MySQL versions 4.1 and above do support them.
I then had to move some accounts to a new hosting account at hostmonster, who allow hosting of multiple domains in a single account. Two birds killed. My MySQL version problem got solved as they used 4.1 and I saved some money by hosting all my domains under one account.