The days of enterprises choosing one smartphone vendor appear to be ending. Forrester reported last year that 60% of enterprises support employee-owned smartphones, and mixed environments are becoming the norm.

BlackBerry was still the most popular enterprise smartphone operating system as of Forrester’s Q1 2010 survey. According to Good Technology’s numbers, iOS is growing the fastest by far. But with more enterprise tools for Android on the market – including new tools recently released by Zenprise and the forthcoming offerings from Motorola and SAP – Android is poised for strong growth.

In the dark horse category are Windows Phone 7 and WebOS. But both got boosts last week, with the Nokia/Microsoft partnership and the new WebOS-based TouchPad tablet.

Which OS do you think will be most popular five years down the road?

Photo by Shereen M