I definitely think that there would be many technological (magical) changes but I don’t have many ideas as to what they could be. I think it would help to look slightly at how Muggle society has changed over time, especially after big wars, and look at how people adapt to these changes, how they remember big events and how they move on towards the future. Notable changes would include social and political beliefs, how they treat others different to themselves, how language adapts, the education system may change slightly, charitable causes will spring up (perhaps some relating directly to the war), the way in which Wizards view and interact with Muggles will probably change quite a bit and great attempts will take place to ensure someone like Voldemort never takes hold of the population again so the media will be looked at I’m sure and stores like Borgin & Burkes will be driven underground so that not just anyone can go into them. Of course advances in technology (magic) will take place. New spells will have probably been created (they have probably been trying to discover a spell which will block the Killing Curse).
Law making will certainly have changed, especially since Hermione worked in Law Enforcement. Hermione, of course, continued with SPEW so the house elves will have been treated fairly and I imagine Hermione would ensure that other creatures were treated well by wizards as well. JKR said that the trio revolutionised the Ministry so you can bet that loads of changes went on inside and that there was a huge political upheaval.
Some info on the Wizarding World after the war from a JKR interview located here
Leaky Cauldron: What, if anything, did the wizarding world learn, and how did society change, as a direct result of the war with Voldemort? (i.e., not as a result of Harry, Ron and Hermione’s future careers.)
J.K. Rowling: The Ministry of Magic was de-corrupted, and with Kingsley at the helm the discrimination that was always latent there was eradicated. Harry, Ron, Hermione, Ginny et al would of course play a significant part in the re-building of wizarding society through their future careers.
Katieleigh: Does Hermione still continue to do work with Spew and is life any better for house elves!
J.K. Rowling: Hermione began her post-Hogwarts career at the Department for the Regulation and Control of Magical Creatures where she was instrumental in greatly improving life for house-elves and their ilk. She then moved (despite her jibe to Scrimgeour) to the Dept. of Magical Law Enforcement where she was a progressive voice who ensured the eradication of oppressive, pro-pureblood laws.
Blodeuwedd: Hi jk, first of all thank you for all the books I have enjoyed each and every one of them could you tell us what professions Harry, Hermione, Ron, Ginny and Luna go on to have did the trio do their final year at school and take their newts?
J.K. Rowling: Thank you! I’ve already answered about Hermione. Kingsley became permanent Minister for Magic, and naturally he wanted Harry to head up his new Auror department. Harry did so (just because Voldemort was gone, it didn’t mean that there would not be other Dark witches and wizards in the coming years). Ron joined George at Weasleys’ Wizarding Wheezes, which became an enormous money-spinner... After a few years as a celebrated player for the Holyhead Harpies, Ginny retired to have her family and to become the Senior Quidditch correspondent at the Daily Prophet!
Steph: Will Azkaban still use Dementors?
J.K. Rowling: No, definitely not. Kingsley would see to that. The use of Dementors was always a mark of the underlying corruption of the Ministry, as Dumbledore constantly maintained.
Natalie: Are house divisions as prevalaent in Harry’s childrens' Hogwarts as in the previous generations?
J.K. Rowling: Slytherin has become diluted. It is no longer the pureblood bastion it once was. Nevertheless, its dark reputation lingers, hence Albus Potter’s fears.