i LOVED viigo!!! and when i made the switch from BB to iPhone, i was saddened to hear viigo was still in a 'we're working on an iPhone app' holding pattern.
for now, you can use apps like NetNewsWire and create a login and then edit your feeds at NewsGator. or there are others like RSSRunner (which i use now) and seems great. if you are looking for push notifications though, i'm not certain which RSS offers this.
but unfortunately, NewNewsWire & RSSReader are news only. sure they do images & whatnot, but no weather, no sports, no traffic, no stocks. man i miss viigo!! it did the work of about 5 apps i now have to use separately. it was definitely a workhorse app for BB.