Re: Do more with iTunes convert and import feature
I do indeed get what you mean. However I don't think there is currently the ability, be it in a third party or natively. Other than for photos from iPhoto of course.
To be honest, I don't see iTunes adding it unless it's a perk of using HD-AAC. Most people don't import as lossless and those that do don't tend to be iPod users. Remember most people who have iPods have their audio at 128kb/s. Why add a feature for ≤10% of your users?
Not only
could Apple do this, but they do it already

If you've got an iPod shuffle, there's an option to automatically convert high bit rate tracks to smaller files (128kbps) for the shuffle. This has been an option, as I recall, since the shuffle first debuted.
I've long argued that Apple should make this feature available for all iPods.
Dan Frakes | Senior Editor, Macworld