Alas, Froyo update for the Samsung Vibrant is available through Kies mini
Not everyone might not be comfortable in pursuing this alternative process, but it appears that the update is available through Samsung's some times wobbly Kies mini software. Granted that they provide step-by-step instructions on installing the update, some people may still be put off having to do some manual work in getting their handset up to par with Froyo. But if you feel up to a challenge, you can follow the directions and find your smartphone finally up to the levels of some newer devices on the market.
However, it's worth noting that there is no 64-bit Windows or Mac support at this time.
source: Samsung & Mobileburn