Cisco's WebEx is one of the most popular tools for conducting online meetings -- you've probably attended several yourself. The service combines desktop sharing, whereby every participant sees what's on the host's screen, with phone and/or video conferencing. With WebEx Meetings for your smartphone (free, for all three platforms), anyone can join in a WebEx meeting from wherever they are and use the phone's voice capabilities for the audio portion. They can also host a meeting and designate someone else as the presenter. The iPhone and Android versions let you schedule and start a meeting; the BlackBerry version lets you start one, but you need a desktop computer (PC or Mac) to schedule it. The Android version also has a widget that lets you access a meeting right from the home screen.
Start by turning to one of these mobile collaboration apps. They don't collaborate directly with each other, for the most part -- they each connect to a central storehouse of information, usually installed on a business's network. Some run on BlackBerrys, some on Android phones, some on the iPhone -- most on more than one. Equip your team members with these and you can extend your business's collaboration potential outside the walls to wherever your workers may roam. The only drawback is that they're not cross compatible.