First off I want to tell you how I came across this bug.. this may help some of you that might have seen the same problem. I received a call from my fiance earlier tonight and while I was talking to her my mother called in. usually when someone calls in a pop up pops up and gives you the options *IGNORE* or *HOLD AND ANSWER*. I found out really quick that those options would not work anymore and the only one that worked was the *END CALL AND ANSWER* <- The big red button on the bottom.
So after looking through some configurations on my phone and Going through a process of elimination I found that the System Notifier Theme *Do Not Touch Me* was the cause of the glitch/bug.
So if anyone that has this theme and has problems then just uncheck it in WinterBoard and you should be able to answer your call waiting calls.
you dont have to delete it in cydia. you can keep it and wait for an update from serendipity or write him an email which in in the package on cydia - [email protected]