Click on the Connections tab. There you'll see your status (either leaf or ultrapeer). If you don't see a connections tab go view > show/hide > tick connections.

Ultrapeers are users with fast connections, a high uptime & who aren't firewalled (that means not seeing the brick wall firewall icon). Ultrapeers handle more search traffic & shield leafs (people with slower connections and/or firewall interference) from unnecessary traffic...searches that don't apply to their shared files

If you want more info, use the forum search or check out this.
http://basis.gnufu.net/gnufu/index.p...s_really_short

Also this thread, though some if it's really old
Do you share or act as an ultrapeer?