Sorry for taking so long to reply.
Yes, i had my car converted in summer 2010 with a system by Versus http://www.versusgas.com/
you can see my car here:
No wayne the car didn't blow up, but it has saved me over £3500 over the past 2.5 years, which after taking conversion costs into account = £2300.
The car runs fine with lpg: engine management has been unaffected, i also had a vap flash lube type lubrication system installed which isn't really necessary on bmw engines but was more of a safe guard measure. This liquid costs me £18 every 6 months and helps to cool the valves as lpg burns at higher temps.
Of note is the fact that my car is just pre-direct injection which was standard from Summer 2007 onwards. LPG is more difficult to install in Summer 2007 BMW onwards due to the change in engine design.
BMW continue the routine servicing and are interested in how it runs, i think BMW themselves are busy developing liquid phase injection lpg in association with prins.