yes.
My set up is as follows:
Shared Mac Mini
ipod touch (daughters)
3gs (mine)
3gs (partner)
I have an old itunes account (pre email address), signed into iTunes on the mac
On all three iOS devices , I go to Settings > Store > Sign in with that itunes account.
On the my ios device, I sign into my icloud account with my @me.com
On my partners ios device, she signs into my icloud account with her @me.com
Daughter does the same.
We do not sign out of the itunes store on the mac, or the ios devices, we share the apps, removing the ones we do not want on each others devices (I have skywalk for instance, but it's not installed on the partners, we all have facebook).
So we all share the same iTunes account, but different icloud accounts.
This makes apps sync seemlessly between mac and all three devices, whilst keeping all the icloud details separate.
So make your first account the iTunes account. If you've bought different apps from each account, then that could be a problem (unless of course they are free in which you can just download them again with the shared account)