It doesn't look to me like Gatherer differentiates between hybrid multicolour and regular multicolour as you say it does, anthonybe. Here is the result of a search for all multicolour cards in RTR, sorted by colour:
[url]http://gatherer.wizards.com/Pages/Search/Default.aspx?sort=color+&output=compact&action=advanced&set=|[%22Return%20to%20Ravnica%22]&color=%20^(|[W]|[U]|[B]|[R]|[G])[/url]
As you can see, the hybrid cards are interspersed with the regular multicolour cards. Also, regarding sorting multicoloured cards just alphabetically: why? What's the point of sorting by colour if you're not actually sorting by colour? It's true that Wizards sorts regular multicoloured cards first, followed by hybrid cards, each sorted alphabetically. This is the order they use for organizing a set by collector numbers. But that doesn't seem very refined, and I don't think it's very useful. Doesn't it make sense for all cards of a certain colour combination to be grouped together? The real question is: what order should the colour combinations be in?
So, let's take a look at how Gatherer sorts all the different colour combinations and see if we can glean an "official" sorting method. A search of Guildpact, Alara Reborn, and Commander (2011) will provide at least one card of each colour combination (including the 4-colour Nephilim, and those weird hybrid/multicolours from Alara Reborn):
[url]http://gatherer.wizards.com/Pages/Search/Default.aspx?sort=color+&output=compact&action=advanced&set=|[%22Alara%20Reborn%22]|[%22Guildpact%22]|[%22Magic:%20The%20Gathering-Commander%22]&color=%20^(|[W]|[U]|[B]|[R]|[G])[/url]
The output seems to follow a logical order... for the most part. It starts with all the 2-colour pairs, then it has the 3-colour shards, then 4-colour, then 5-colour, and then, for some reason, the 3-colour wedges. So the first part of a colour sort is # of colours, excepting wedges. The secondary sort within colours is in WUBRG order according to the order in which the mana symbols appear on the card, except, again, when you get to the wedges, in which case order doesn't matter (in the Gatherer search, it's sorted alphabetically after colours, so they are just in alphabetical order). So it seems like the wedge cards were just neglected and tacked on at the end, which I don't think should be used as the basis for a proper colour sort.
Also note that there is an official order for how the mana symbols appear on cards, which is to go clockwise around the colour wheel (WUBRG) while leaving as little space as possible between the colours you're using. For example WU instead of UW, because UW has BRG between it, and GWU instead of WUG, because BR would be between U and G. This breaks down a little with the hybrid/multicolour mix cards of Alara Reborn. These cards, like
Bant Sureblade, are grouped with the rest of their respective colour combination, disregarding the actual order of the mana symbols, which always places the hybrid part first. This shows that what's important is the base colours of the card, e.g. GWU in
Bant Sureblade, even though with the hybrid symbol coming first, the order on the card is GUW.
As for wedges, the order is to put the common enemy first, followed by the allied colour pair. To be analagous to the colour pairs, I would say that all 3-colour combinations should be grouped together and sorted in WUBRG order. I think a complete colour sort in ascending order should look like this:






Azorius

Orzhov

Dimir

Izzet

Rakdos

Golgari

Gruul

Boros

Selesnya

Simic

Esper

"Dega"
Grixis

"Ceta"
Jund

"Necra"
Naya

"Raka"
Bant

"Ana"






Artifacts
Lands
I think another valid option would be to sort it mostly the same, but within colour pairs, group allied colours first (WU, UB, BR, RG, GW) then enemy colours (WB, UR, BG, RW, GU). Then, in 3-colour combinations, group shards first (WUB, UBR, BRG, RGW, GWU) followed by wedges (WBR, URG, BGW, RWU, GUB).
Does anyone else have any thoughts on a "correct" order for sorting by colour?
Edit: Addressed another issue I thought of. Also, the URL tags aren't working properly, and when I leave them off the forum doesn't display the link properly, so you'll have to copy/paste the links yourself if you're interested in seeing them
