in rfic/mmic people are pushing cmos and sige technologies higher and higher in frequency, because, i think there is really nothing else to do ! they are doing 60GHz Wireless LAN with capability of doing 1gb/s in data transfer and trying to do this in cmos and sige pushing the technolgy as high as it can go.
people already tried to do this with gaas phemt and gaas hbt as well as InP but of course, they are too expensive.
this is all for mm-wave systems of course.
lower in frequency, cmos in particular just trying to lower costs and integrate as much as you can.
multi band is the hot issue right now and using as many frequencies as you can.
transmitter design is also hot right now, and all digital solutions, doing all the rf processing not using mixers and filters, but using digital filters and the ADC/DAC. silicon technologies and tools are finally good enough to make this a reality, at least in the lab.