Potentially it can overwhelm the bus, at least that's what this ZDNet review of the Fusion IO SSD drives says. That's kind of amazing, especially when they say that people that are using this drive can't use SATA architectures and are turning to PCI-E instead.
Wes Brown has said his company has a couple on order, so we'll get a first hand review here soon, but in the meantime there is some interesting information in the ZDNet review.
First, these things are expensive. AU$12,500 for a 650GB set of drives and US$900 for the 80GB "gamer" version. That's quite a price tag, and I expect only those enterprises that are really struggling for I/O performance will adopt these anytime soon.
I have been worried, as have many others, that the nature of memory based flash chips isn't something we want to rely on for our enterprise applications. However the article had some interesting notes in it. First, Fusion does a lot of redundant checks at various levels to ensure that data is correctly written and there are extra NAND chips to ensure the drive can keep up with the volume under load. There are 25% more chips than needed, to better cope with these checks, as well as provide some redundancy and leveling of the writes across the entire drive.
Performance is amazing, as you can see from this chart above. It far, far, out performs the mechanical drives. There are other graphs in the review as well, and if you have a big budget, with high performance needs, I'd urge you to check this out.
Unofficially, I know a few long term SQL Server users of this drive (> 6 months) that are thrilled with it's performance under load.