Well, it is a blast attack ... since every target takes the same damage (unless you sneak attack somebody), you could look at it this way:
The rogue throws one magic shuriken. It splits into 9 and recombines.
Hey, it's magic.
I mean ... you could use a thrown weapon with the Ranger 1 daily Split the Tree ... you use the same attack roll there!
Also, I been thinking about the stupid sword throwing paladin, and I'm gonna go silly-like.
Build: Yellow (as in coward) Valkyrie.
Magic thrown sword. Either a drow long knife or a farbond spellblade as chitzk0i mentioned earlier.
Contagious challenge.
Half-Elf MC bard to *cough* pick up twin strike + versatile master + combat virtuoso.
Stat dump wis to 8, and invest in dex.
Champion of Corellon for silly amounts of AC .. and increased movement speed in plate.
Idea is to Divine Challenge foes in the middle of a clump, twin strike to mark (with divine sanction) two other foes adjacent to it, then use the run action to piss bolt around the corner (or graceful step over difficult terrain .. whatever to get out of dodge).
It will be the most hilarious paladin ever.
Actually, it looks to me like elegant strike + graceful step already makes champions of corellon play somewhat skirmish-like.
Edit:
Oooh, and on the subsequent round, peek round the corner and throw sword again ... if someone gets bloodied or dropped, shift 1 square back into total cover.
Muahahaha.