Just to say, that Klog has made a very sensible point; its no good granting a huge number of warrior tanks or priest healers 'Raid Ready' status, and telling them they can all expect to raid most of the time. For a start, that would by lying, and also it'll take forever to get them all geared.
You'll see on the Raid Wing list that certain classes and roles are 'closed' once we have enough. This is to help us maintain a sensible balance, and to be used as a guide. If there is an outstanding application from one of these roles, we will look again at the existing members and whether they can be accommodated, but we're likely to be much more strict over those sort of applications, so it is a guide for you, also; if we have too many of one role, consider a respec or one of your imba alts as your main raider.