I previously reported that Samsung had pointed to July 21st as launch day for the Samsung Vibrant, T-Mobile's variant of the Samsung Galaxy S. Now, TmoNews has heard it through multiple sources that T-Mobile will launch the Vibrant a whole week earlier than expected, to July 15th, possibly in a move to better compete with another handset launch on the same day.

Verizon will launch the Motorola Droid X on July 15th, and it seems that T-Mobile doesn't want to leave all the press covering only the Droid X launch. Plus, with the Droid Incredible, EVO 4G, and iPhone shortages, the sooner they get their device out, the better.

AndroidandMe notes that besides the Nexus One:

The Vibrant is the first high-end 1 GHz Android phone to land on T-Mobile, so it might attract a bunch of customers who have been waiting to upgrade their handset. Of course there is always something faster around the corner, but the Vibrant’s beautiful display and super-fast GPU might make this the sweet spot to jump in.

AndroidCentral suggests some other possible ideas behind the date change:

Maybe T-Mobile decided to get in on the party a little early to time with Verizon's Droid X launch, or maybe they just love us more than we thought.

Following is a leaked document posted on TmoNews to go along with the claim:

Anyone here planning on upgrading your T-Mobile phone to this?

Other Sources: AndroidandMe, AndroidCentral, Phandroid

Images from AndroidandMe and TmoNews