There are a number of legitimate games wholesalers in the UK, Hong Kong and other countries, as well as on these forums, that are selling region free Xbox 360 and PS3 games.
Many of the games are previous releases like GTA IV, older EA Sports titles, etc.
But some of the games advertised as region free are the new GTA: Episodes from Liberty City, Call of Duty Modern Warfare 2, the new EA Sports 10 titles (FIFA 10, NBA 10, etc.), Dragon Age: Origins and Assassin's Creed 2.
These sellers usually advertise the region free games as being compatible with NTSC-J consoles, PAL consoles and NTSC US consoles, but actually list the official region they come from.
For example, Call of Duty Modern Warfare 2 advertised as region NTSC-J, but region free.
Firstly, is it true that these games will in fact work on any Xbox 360 or PS3 console?
If the above is true, I have one more question. A number of people I know both in and affiliated with the games industry have told me that Xbox Live and the Playstation Network lock out users attempting to play a region free game imported from another region

(No confusion intended)
I do not want to import these games only to find customers complaining they can't play online, or can't unlock their limited edition items, or can't play the game at all
Any assistance regarding this matter would be immensely appreciated.