Harry - 6:29 pm on May 3, 2012 (gmt 0)
Years ago in one of the forums, I had a debate with people about the value and ethics of designers stamping their Designed/Developed by all over their clients' sites. I'm still very against clients subsidizing advertising for service providers. It's an ethical issue for me. I'm glad that Google is following on that form of link abuse once and for all.
I would say, if your app is a freeware, then, yes use the footer link. But if a client paid for a service app and unless you offered them a discount to have link on their site, basically paying them for the advertising space, remove the offending links.