I've notice that each wall post from mobile phone will have something like
44 minutes ago via BlackBerry
3 hours ago via iPhone
and if we click on word "BlackBerry" or "iPhone", it'll redirect to
http://www.facebook.com/mobile/?v=6628568379 (for iPhone)
or http://www.facebook.com/mobile/?v=2254487659 (for BlackBerry)
Is there anyway we can FQL for user's friends with specific phone (or access "v" value) by using these source above ?
There's no way to query specifically for 'friends who use a certain device', but via the news feed you can determine this for some users
Check out the 'stream' FQL table: https://developers.facebook.com/docs/reference/fql/stream/
With an access_token with the read_stream permission for one of your users you can go through the posts in their news feed and check the app_id column to see which app was used to post the story. Obviously this will only surface devices for those users who've recently posted something which is visible in your app user's feed, but it's a start
As you've noted, the mobile clients are identifiable from news feed, some of which are:
A sample query which seems to give what you want is:
select actor_id, app_id from stream where source_id = me() limit 500
The answer to this looks like:
{
0: {
actor_id: <snip>,
app_id: 74769995908,
},
1: {
actor_id: <snip>,
app_id: 6628568379,
},
2: {
actor_id: <snip>,
app_id: 6628568379,
},
...
From this i can see that the first (snipped) user uses Android, and the next two use the iPhone app