I thought that the usage of the phrase was a regional issue until I heard an MSNBC reporter use it yesterday. It's a growing trend and technically, it is grammatically incorrect.
Here's why:

The most common misuse of the phrase "on tomorrow" occurs where "tomorrow" is used as an adverb in a sentence, i.e.: "I'll return this report to you on tomorrow." Adverbs can not be the object of a preposition.

Part of speech is dependant on function within the sentence. If a word is used as an adverb and is acting as an adverb in the sentence structure, then it is an adverb.

The word "tomorrow" already includes the IMPLIED prepositions "on" or "to" and was once written as "to morrow". Later, hyphens were added (to-morrow) and then eventually, the words were joined without the hypen (tomorrow). "Yesterday", "Today" and "Tomorrow" do not require the preposition "on" for the same reason. "On the morrow" is already implied with the word "tomorrow". Adding "on" or "to" is redundant.

Generally, the preposition "on" is paired with holidays, specific days of the week, or dates. This has been the practice from Old English to the present.

Examples: on Christmas; on Bastille Day; on Friday; on Monday; on May 15th; on October 2, 2009.......

Had the sentence read "On the morrow, I will return this report to you", it would have been a correct, albeit obsolete, use of the phrase "on tomorrow".

I hope this clarifies the matter. For the record, I live and work in Memphis. I hear the phrase daily.........and it makes me cringe every time! I thought it a reflection of the local school system. Should I be glad it isn't just a local trend?

(I'm more and more thankful for the private school education I received! I think my parents daily!)