I just bottled my smoked (rauchmalt - 2 lbs) oak aged porter a week ago and it tasted great! I'll let y'all know how it tastes when I crack one open this Friday.. I just don't think I can wait a full three weeks.
Anyhow, I used medium toast french oak chips 1.25 ounces and let it sit in there for 2 weeks. The oak taste didn't seem overpowering but it was a noticeable addition to the smokiness.. kinda like drinking a campfire :rockin:
Anyhow, cubes probably will not have the same effect as chips since they have less surface area. There is also supposed to be a difference between french and american oak as well with french generally being the more desireable. I researched this a bit and found that there is no agreement on how to add the oak, some say to soak or boil the chips and add the liquid to the secondary, others say add only the chips after soaking or boiling them, some say add them without soaking or boiling, and still others say to soak or boil and add the whole mess. Do whatever seems right.
I soaked them for 24 hours as it was supposed to possibly let any astringent tastes out of the oak and lessen the tannins that make it into your beer - kinda like using a used oak barrel vs. a new one. The instructions on the bag also suggest that you soak them for 12 hrs.. I did taste the oak water and it tasted pretty good but I elected to no add it. I did steam the chips real good over their own oakey juices. I think microwaving would be fine as well. I don't know about boiling..
The people at my LBHS said sanitation wasn't much of an issue since the oak chips were dry and, like the fat girl at prom, nobody's much interested in the oak. Besides, the beer already has a good bit of alcohol in it at this point.. (I know everyone thinks those guys are generally uneducated but I do trust my guys, they seem to really know their stuff).
As for your IPA, I was browsing some archives and came across a discussion of oak in an IPA and there was some disagreement but these were the three general possibilities from a historical perspective:
1. The oak barrels were reused for each trip and so the presence of tannin flavors was unlikely. So, you should soak your chips before adding to mimic this "aged/used" effect.
2. The trip to india was a long one and the barrels were cheap so there's no reason to expect that the empties were saved and brought back to be reused. So, tannin flavors were probably present and the chips should be added without soaking or the juices should go in along with the chips.
3. the barrels were lined with pine resin (tar) - I don't think you'd want to duplicate that flavor in your IPA.
Of course, there's no reason to try to do it like they did in the old days.. do whatever sounds good/right and let us know how it turns out.