I am designing a new VMM fabric for our data center but have seen an article (that i now can not find) that states the gateway has to be .1 for each network as opposed to for example .254.

it stated that this was not a preference but a requirement.  The articles i have read on  VMM gateways do not highlight this although all the illustrations do have a x.x.x.1 address as the gateway . Can any one confirm this or post a link that says otherwise.

Ultimately.....

If i am using my existing VLANS for separation then I use my current IP subnet/masks/gateway configurations. 

if i want to adopt and utilise VLANS with network virtualisation the gateways would have to be reconfigured on my subnets and they would have to be on the .1 address.