From the frontend yes and it also is presented this way in the created ruleset, however the roundrobin still is used without weighting. We did some tests with that and billm did some debugging and knows why it is not working. This behavior can't be changed atm.
If you want HTTPS and SMTP on one WAN only make sure it is one of the reliable ones. We don't have interface failover (if WAN dies use WAN2 for example) in pfSense 1.0. This is something that already is worked on in HEAD. The poolfailover however will work.
There are also some (poorly written) webservices that won't work with plain HTTP or other protocols and multiwan. You should add an hosts alias for these destinations to add IPs to when you encounter problems and send these out one of the WANs only by creating a rule for this alias destination.