However I am curious exactly what rogue power it is that will give you multiple attacks... There is exactly ONE at-will power in the entire game that does that, Twin Strike. Pretty much the only way to get Twin Strike as an at-will if you are not a ranger is to take an MCPP in ranger.
There is another at-will in Martial Power, the Fighter At-Will Dual Strike, though Twin Strike is a far superior power; it allows two ranged, or two melee attacks and keys off of different attributes.
Also, the easiest way to get an at-will from another class is to play a half-elf and take the paragon feat Versatile Master from PHB II
Cheers!