Tigole has confirmed that content patch, known as 3.0, which will hit live servers before Wrath of the Lich King, will also include a decrease in XP to level from 60 to 70.

Here's a reminder of what else we'll see in 3.0 (which is yet to hit the Public Test Realms, so might still be some time off):

Blizzard Quote: (Source) With the release of Wrath of the Lich King approaching, we wanted to provide you with some important information. In preparation for the expansion, we will be issuing a new content patch in the coming weeks. Much like the patch made available shortly before The Burning Crusade's release, this content patch is designed to bridge current game content with that of the expansion and will contain some exciting changes and additions.

We have outlined some of the larger features scheduled to release with the patch below:

New class spells and talents
Stormwind Harbor
Barbershops in capital cities
Zeppelin towers outside of Orgrimmar and Tirisfal Glades
Two brand-new Arenas featuring challenging new layouts, terrain hazards, and moving obstacles
Guild calendar
Hunter pet skill revamp
New profession: Inscription

As mentioned above, this is not a comprehensive list, just some of the major highlights. We’ll post the full patch notes as soon as they’re available. Regarding Inscription, please note that all Burning Crusade players will be able to select Inscription as one of their two professions and level up to a skill level of 375 with it. Upon the release of Wrath of the Lich King, players who purchase and install the expansion will be able to continue leveling in Inscription and the other professions beyond 375.