Possibly. I had all kinds of problems with Airport and the Seimens Gigaset wireless phones. I've since switched to using a GSM mobile provider for all my voice traffic, so I haven't investigated further to see if different channels on the phone helped, or if there was any way to sort it out. It's possible that newer implimentations of the phones would interfere less, though.
The biggest problem I had was that when I used the phone, 802.11b traffic would slow way down, like using a 300 baud modem. Awful.
The answer is a definite, maybe. My neighbor has a problem with his phone and wireless connection, though for him it affects the range in which his ap can reach (this is easily repeatable).
I have another buddy who has problems with his 2.4ghz video transmitter interfering with his wifi (and vice versa).
But then again there are others who say that they have 2.4ghz phones but don't have a problem (at least not one they notice).
Probably the best thing would be to test it out if you can. You could always go above (5.4ghz phone, only a potential problem if you have 802.11a) or below (900mhz). I have a 900mhz DSS phone that works great, and it only interferes with our 900mhz baby monitor (sigh).
Chances are that if you're clients are usually close to their ap's, you probably won't have a problem.
There are only 3 unique channels in the 2.4 GHz spectrum. So the phone and the AP are going to be constantly tripping over each other if you don't lock them down into separate channels.
The second problem is that 802.11 does not use a good deal of power (about 50 milliwatts) while the phone puts out a great deal of power. So you basically are trying to whisper in a room where someone is shouting.
The reasons that people have so many different experiences is mainly due to where they put their phone. If your phone is located inbetween your computer and your AP, you will have problems. However if you had a setup like (Phone .... Laptop ... AP) you won't have as many problems (possibly none as long as you never walk between your computer and the AP while you are on the phone). Plus if you aren't using the computer when you are on the phone...then you would never really know if you have problems.
My suggestion would be to get yourself a 900 MHz phone for 2 reasons. 1) They are cheaper. 2) The have longer range (don't believe me? Check out a physics book, longer wave lengths travel further. Why do you think some psychopaths are listening for radio waves from Aliens??)