Verizon and ATT don't offer "truly" unlimited. Those grandfathered plans often get speed capped. Now, I'm not sure how Verizon is handling that issue with their LTE, but I do know they and ATT will severely speed punish an unlimited 3G account for going over a certain amount of data. ATT just adjusted their speed cap policy to be anything over 3gb.
I'm grandfathered, so the below doesn't apply for me. Even if it did, I've never been over 10 gigs, and usually fall between 3-5/month... Doubt I'm in the top 5%.
I have wifi both at home and work, so more often than not I'm not on their data network.
**broken link removed**
Verizon announced some substantial changes to its data plans today, implementing speed throttling for heavy users. According to its statement, the throttling will only take effect if you subscribe to a data plan or feature February 3, 2011 or later. Existing users will be grandfathered into the current policy until making a change to their account. Only the top 5% of data users will be affected by the throttling addition, the majority of users will remain unaffected.
Verizon also discusses a transparent content-remastering feature which will automatically scale images, video, and other data-heavy media to use less bandwidth when being transmitted to your device. This includes such techniques as transcoding video on the fly, which will result in "blockier" video and more JPEG compression artifacts in images.
The optimization technique works via a transparent proxy on port 80. This means the majority of web traffic (intended for viewing on a mobile device or not) will be "optimized". One work-around to avoid this compression would be to host a website on an alternate port such as 8080, which won't be affected.
Additional bandwidth saving techniques will affect the buffering of video, no longer will you be able to load an entire video before playing it; Verizon's optimization system will cache the video on their servers and stream with a small buffer.
AT&T has a similar practice when utilizing their proxy. The key difference being that you can disable AT&T's proxy by simply not using it, while Verizon's implementation is transparent and not controllable by the user.