OK so I was reading through the DEV quotes, again, and they where mentioning the ability to buy houses in every town. Cool. So you stash your stuff there and think you are mister big dude with all your armour and plunder.
What if the Radiant AI happens to have a NPC who is a theif, what if they then see this house that is always empty cause the guy who owns it is always out adventuring.
You get back from a hard day adventure down some dungeon and as you enter your abode a message comes up "As you return home you notice all is not right, you have the suspicion you have been broken into".
Then you have to investigate your home and find clues that are left.
(I would imagine the selection of what was stolen from a mod point of view would be random as you wouldn't know who had what)
Then it is off to search for the theif. Added info could be included to core NPC's in the theives guild and extra NPC's can be added to help track down the theif.

I hope that something like this is actually in the game but it could make a fun mod
especially if the thing stolen was valuable and you REALLY wanted it back.
Would be good for the none Theif charecters to expose them to the seedy underbelly of the various towns.

I believe that Bethesda have ruled out NPCs robbing the PC's stuff from houses, because they say that players often mistake things like that for bugs.

However, if you did it your way, with an explicit message making it clear that it's something's missing, it would be clear that it wasn't a bug.

If it was a one-off, and you got to carry out a quest-like investigation to retrieve your stolen property, it could work. Also, IMHO you'd want to limit it to only a few (or maybe just one) big-ticket things, rather than losing lots of stuff.

It would be annoying if your possessions were constantly being pick-pocketed, house being broken into and random items stolen, etc. But as a focussed, one-off event, I like it.

Also, since it would be a mod, players who don't think they'd like it would simply not download it. So, I think you've got a good mod idea here.

Yeah could get annoying
Maybe the frequency of break-ins could be related to which town and what part of town. Not having seen what these towns are going to be like or how big or where the houses for sale are it is hard.
I don't imagine that the house for sale would be random though.
Maybe part of the mod would include protection money to the theives guild to keep your house safe. A bit of the plunder from your adventures handed over now and again. A note left on your door asking for some of your stuff to "be looked after cause it is a rough area you know" that sort of thing.

Or maybe you could "make an example" of the thief the first time, and the guild will leave your houses alone after that

I don't like the idea of paying protection money - seems a bit craven for a heroic TES main character.

Also, once you've gone through the process of getting your stuff back once, the novelty will wear off pretty quickly. So, IMHO you'll definitely want some reason in the mod that it won't happen again.

Actually: in Fallout2, when some guys stole your car, if you didn't gun them all down when you caught them, they were actually quite useful. Maybe you could have a choice at the end like that - either the PC murders the house robber, scaring off future robbers, or he/she manages to reach an agreement/do a favour for the thief, and will thus get favours back (including being exempt from house break-ins in future).

Maybe the PC tracks down the thief, who then tries to escape. In doing so, he stumbles into some daedra or something, and the player can save him. In gratitude, he promises to have the player's houses noted as off-limits at the guild.

not a bad idea. maybe you could even just have the message say that 'something was stolen' without actually removing one of the items. or making a stealable item specifically for that quest.

Nah I reckon losing something would be better, that way you would really want to get it back.

I like the idea myself, though yes, it could become deeply frustrating. There would need to be an advanced security upgrades system included in the mod, for upgrading locks, windows etc. even recruiting guards.

Guards are a great idea.
I think for immersion the theives guild was too easily avoided if you where just a mage. Morrowinds interlaced Fighters and Thieves guild storyline was great. I had a really hard time trying to become Master of both, you had to get the orders and take them out in just the right order otherwise it wouldn't work.
A rich adventure would have to choose to either get in bed with the theives guild or be under threat from them.
Maybe in the quest to retrieve your goods and you save the theifs life to garner the protection of the guild you could also recruit some Body Guards to look after your place, and keep you safe in town.
When ever I got back to my place in Morrowind from some quest I would change out of my armour into appropiate city attair. Always thought that it was weird that average citizens would happily trade and talk with some one in 300lb of Deadric armour and a sword drawn.
I bet Oblivions Radiant AI wont take none of that sh!t.

Yeah, but in Morrowind, if you notice, when talking to someone while having your weapon in hand, they don't like you as much as they do when you don't have your weapon out, it didn't make much of a differance, it's only by like five points, but i'm sure in Oblivion, it'd be neat if they asked you to put your weapon away or something like that.