I have a Logitech clearchat headset that runs on 2.4Ghz wireless frequency. I'm thinking of getting a Logitech Desktop Wave Wireless, also running on the 2.4Ghz frequency.
Will I be able to use keyboard, mouse and headset without interference?
Theoretically, it does (that's why Jobs complained about the number of MiFis at WWDC this year), but it doesn't truly matter (which is why two devices on a WiFi network can still operate pretty well at the same time). Unless you have a Wireless Keyboard, Headset, Mouse, Wireless iPhone Syncer, Baby Monitor, Thermostat, TV Remote, and a Robot that predicts your every need all running on 2.4Ghz, you shouldn't have problems with them.
That said, make sure you'll keep your receipt or receipt email. If you find that it doesn't quite work, you can always return it, and then you'll have only lost time and gas.
Most likely no issue here, unless you have a lot of wifi traffic in your area, or try to type/talk when someone is microwaving a burrito. These devices actually auto-negotiate in the 2.4 Ghz spectrum, finding gaps large enough to send their signal through.
However, if, say, you live in an apartment complex with 8 of your neighbors running wifi routers, you may have issues due to the spectrum being flooded. This is the situation I am in, and I've decided that wires are not so evil after all.