Actually 1and1 is running 5.2. Some web software does meanwhile requires 5.3. After all software will break even when there is no upgrade at all.

Anyway, i fully agree: providing hosting is a hard business. Imaging what 1and1 needs to do for this huge server farm... wow. It's ok for a lot of low traffic sites without much functionality, but in my case I needed more at one point. Now I have the choice between 5.3 and 5.4. Thats neat.