domain and 2 linode account

Simple you just need to add an A record for the domain to linode A and an A record for the subdomain to linode B

hi Obs,

thanks for the suggestion, ya it seem like that's how tumblr,posterous handle the custom domain ? just add a A record in my dns management in order to point my subdomain to them.

but what I really wish to know is do i need to setup anything on the "Account B" ? to make it respond to the A record i set in "Account A"?

thanks.

Nope, you should be fine.