I have tried the mobile platforms of Forex.com InterbankFX and GFT.
Forex.com - is a WAP webpage, very limited functionality (no charting), however you can open and close trades, set/change stoploss/takeprofit
InterbankFX - is
Metatrader Mobile, very nice, especially on my square screen HP hw6515. It has the most functionality, charting, with easy to apply indicators and trendlines, the application loads quickly and is very reliable. It is also very simple to enter or edit trades. I switched to InterbankFX primarily for their trading software.
GFT - The mobile platform for PocketPC is java based, you have to download and install IBM's java for the PocketPC, it is slow to load, and doesn't work well with my funny shaped square screen. What is more, it is more difficult to enter trades with the GFT mobile software, you have to leave the charting screen and it is definately less intuitive.
The great news is that both InterbankFX and GFT offer free trials including use of their PocketPC software.
HTH
Rious
fx4u.blogspot.com