Usually when I post multiple photos onto one thread I host them on my own server. After a certain amount of time lapses, usually a year or so, I delete the photos (a) because I will incur overage & bandwidth charges if I'm not careful about how much stuff I keep on there, and (b) because after a while the relevancy of the photos fades.
If it was easier to batch-load photos directly to Vacuumland, I'd gladly do so (thinking in terms of how you can do this on Facebook now).