Input devices and their software take a step forward. Specifically, improvement in voice recognition, and mouse gesturing/Wii controller applications. No killer ap implied here.
Free software expansion continues, as Intuit finds competition for Quicken in the home and small business marketplace from low cost/free alternatives.
Everyone waits for the hardware of cellphones to catch up to better software for phones, so a prediction here is for no huge leap for cellphone software. Windows Mobile 7 doesn't bowl over anyone. Jostling for position as to the #1 seller of phones isn't important because most of the software advances has to do with the phone/web interface, and the extra charges for web access is reaching its peak in many markets.
New rootkits for Windows, and separately, one for a select few versions of Linux.
Linux users will promptly declare that there's no such thing as a true rootkit for Linux and blame lax password procedures for their problems as well as lack of dates on Friday night.