Thought I'd tap into my notes from school to help explain the difference between MHz for CPU and Phones.... here goes:
Frequency with telephones and frequency with CPUs are completely different things. The term frequency itself just refers to the amount of times something happens in a second. One Hertz (Hz) equals one cycle/signal sent/etc per second.
When GHz are reffered to with telephones (wireless), 2.4GHz refers to the frequency range that the cordless receivers use. Most cordless phones use either 900MHz (cheaper phones) up to 2.4GHz (better phones). The frequency range is just the frequency that the radio waves are sent at. The higher the frequency, the better and faster the transmission. All wireless devices that use radio waves are assigned a specific frequency range to operate in...everything from radios (FM being 88 -> 109Mhz), to Wireless Ethernet (2.4GHz - 2.48Ghz, some variances...), GPS, satelite (yep, they're radio, just concentrated). Main reason for such variance in frequency is to avoid interference. Also, each frequency range can also be divided into sub"channels" for further avoidance of interference. The higher the frequency's have better quallity, hence devices that benefit from such use those ranges (networks, satelite, cell phones, etc), whilst lower ranges are assigned to devices that do not require such high frequency (audio radio). In short, frequency with radio is measured by the number signals sent per second. Hz = one signal. MHz = 1000 signals, GHz = 1 million signals.
CPU frequency is alot easier to explain than radio waves. With CPU, Hz refers to the number of cycles that the processor processes per second. The main reason that CPU's have seemed to lag behind radio is simple.... radio doesn't process information, it is just a message of range. CPU processing creates heat, alot of heat. CPUs therefore can only process so much info without catching fire (literally). With upgrades in technology, more transitors are fit onto processor dies, theorectically allowing higher clock speeds....ie more GHz. Moore's law when studied properly explains this in more detail. (Although with recent synthetic diamonds being produced at a cheap price, if CPU manufacturers take advantage of them, look to see EXTREMELY fast CPUs running super cool compared to modern CPUs).
Phew.... hope that explains things a bit... I paraphrased most of my notes, so I hope I didn't leave anything out. :P
