Whilst I would not expect (and wouldn't want, for that matter!) to be able to actually join any of the Dunmer Great Houses in Oblivion, it'd be interesting if there were quests for (or about) them - I'm sure they would have some business dealings with Cyrodil.

Do any mods out there feature any Great House-related quests or the like?

OOO
And
Integration: The Stranded Light

bring up lore from past Oblivion games and the political going ons in other provinces.

OOO has maybe a very vague reference to the great houses, and Integration has a Telvanni thats wanted dead in Morrowind hiding out in Cyrodiil, and she helps you out in a few quests (including growing your own Telvanni mushroom city). Haven't heard of any other mods really containing a lot of lore and references like that. Integration also has a relative of http://uesp.net/wiki/Morrowind:Crassius_Curio from Morrowind, and a lot of other references like that.

EDIT:


Description contains:
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