I have never heard of a VST 909 style drum sequencer. Maybe it's not possible to implement such a thing into the VST protocol. However if you are looking to synthesize drum sounds like 909 and 808 and other cool percussion sounds and effects I suggest you check out Waldorf Attack VST.
The best drums I have used so far I think have to be Reaktor ensambles such as DSQ 32 and Bi Machine. Though these are not nesc 909 emulations they are fat and raw. The Waldorf I find adds a wierd bit of distortion that can be good or bothersome at times, because I think its sample based. If I need just a dry kick or close to a 909 sound I do use the LM7 at times. Haven't tried the LM4 yet. Of course good technics in the mix also matter to get the most out of anything you use.
But we already know that