Although I have access to my 20GB of space on my iDisk with my MobileMe account (family pack), it's hard to ignore some of the great FREE alternatives out there. Dropbox is a great service for people that want to share large files. Most email services cap the size of the email that you can send to anywhere between 15-20mb per email on average. While that's probably plenty for your JPG pictures, it's definitely not enough for video files. With Dropbox you signup for a Free account and then you can access up to 2GB's of online space from your computer or your iOS device using their FREE Universal App. Not only can you access your files for sharing, but if they are in a compatible format you can view them right in the App too. So for example, if you upload a PDF you can view that PDF from your device. Many apps offer this type of viewing. What makes Dropbox different is that you can also elect to send someone a LINK to the file so that they can download it from YOUR Dropbox. This way instead of emailing the large file, you're just emailing a link that they can click on to download the file to their computer. This is also a great solution for having an online backup of an important presentation. Since it's also web based you can access your files from any computer on the internet by going to dropbox.com and logging in.
iPhone 4 users can share HD video
It's great that you can shoot 5MP stills and HD video from your iPhone 4. With the Dropbox App you can upload those files directly from your camera roll to your Dropbox account and share them! If you need more than 2GB of space there are paid options starting at $9.99/month.
Although it's great to be able to send/share files from your camera roll, I would really like to see this App updated with to register itself with the "Open In" command. For example, if I already have a PDF on my device in another App, I'd love to be able to say Open in Dropbox to share that PDF.