EE2 is basically dead, currently for version MC 1.2.5 (What Technic/Tekkit uses). EE3 is where development will continue. However, it has a minimum MC version of 1.4.2. A low priority for Pahimar is updating EE2 to work on MC 1.3.2. Therefore, as tekkit will almost certainly use 1.4.2 as a base, it will use EE3.
There is a PRERELEASE (i.e. ONLY A FEW FEATURES IMPLEMENTED, LOTS OF STUFF NOT WORKING) available for 1.4.2 here.*
Some changes (from the thread):
The mod is changing in a lot of ways, arguably for the better. Maybe this version will not be disabled on the majority of servers. One change with EE3 is that it is now open source (available on github), so now there is no problems with permissions.
Some things to note (gathered from various sources, including later posts in the linked thread):
Dark matter tools will still be present (with their destructive powers).
Extra speed will be given with boots of the swiftwolf.
Flight will be given with boots of the direwolf (replacing the swiftwolf ring)
*NOTE: This will not work with the current version of Technic/Tekkit. You will need to mod a current minecraft version.