Sony's upcoming PS Vita handheld come in two flavors: Wi-Fi or 3G. The Wi-Fi is $250 and the 3G is $300. In the U.S. your carrier is AT&T. Even worse, you're restricted to only 20MB per download on 3G. Looks like you won't be downloaded those high-definition games over the air after all.
Boo all you want, but that's the price gamers have to pay when Sony chose AT&T to be its official U.S. partner in providing 3G service for the Vita. As with the iPhone and iPad, AT&T caps those devices at 20MB per download too.
For the record, Sony says the limit was set by AT&T, which means it download caps may differ on other carriers in other regions.
On the iPhone, if you need to download a huge game like Rage over 3G, you can't. A prompt pops up telling you to switch to Wi-Fi to complete the download. It's likely a similar notification will be present on the 3G PS Vita.
If the limit is 20MB per download, what will you be able to download? A song, small in-game DLC, maybe some bite-sized PSP Minis. What you won't be downloading are any digital copies of PSP or PS Vita games available on the PlayStation Network — a real shame considering physical and digital copies of the same game will arrive at the same time.
The choice is now even easier for most people: Wi-Fi model it is.