I've been testing both systems now. Unfortunately Orkut was a bit disappointing as the servers are very unstable and I find myself reading it is down again and again.
Yahoo's 360 & Microsoft Wallop on the other hand seems quite stable. Yahoo is very new but I like the way they have integrated their IM to the service. It gives you 10s of invitations so I sent out a lot to my friends and they already started to sign up :)
Wallop is flash based and therefore has a very cool interface. I tend to right click now and then though :) I've found out how to delete a post (picture or music). Help does not really help as it does not have much information in it but Wallop team is very helpful and responding quickly to questions.
They keep on adding new feautures and fixing bugs one of which is about importing your RSS from another site. I learnt that they will fix it soon. One of my contacts in there told me to re-importing the next day is a workaround. I'll test and see.
In the meantime, blogger.com acts up time to time and I am still looking for a better blogging site. Both Wallop and 360 allow blogs but they do not have the bells and whistles...