The use for the prefiexed properties is to avoid collision between how a vendor renders it and how it should work (based on W3C). These properties will eventually disapear (for the current properties) and will eventually re-appear for new prototype properties.
One thing to keep in mind when using vendors prefixes, define the prefixed properties before the final one, this way, for example, when
border property will be final you won't have to rewrite your css.
This way, each vendor that doesn't support the final format, will support his own and each vendor that support the final format will interpret the two definitions they understands but the second one will overwrite the first one.