Yes, texture2D() is deprecated as of (at least) OpenGL 3.3; see page 99 of the 3.30 GLSL specification. It will continue to be supported in OpenGL compatibility profiles to avoid breaking existing code, but its usage in new code is strongly discouraged.
EDIT: The details are slightly different for OpenGL ES, but the end result is the same: texture2D() was deprecated and replaced by texture() in OpenGL ES 3.0; see section 8.8 of the 3.0 GLSL ES specification.