Regarding lightmapping solutions, I noticed no one has mentioned Sunflow on the Irrlicht forums. I just wanted to point it out:
There is an exporter for Blender that saves Blender scenes as Sunflow files. Sunflow then calculates global illumination based on different techniques you can select.
The important thing is that it can render the lighting results using existing unwrapped UV lightmap coordinates. This means Sunflow can render into lightmap textures that you can then apply to your models in Irrlicht/Blender.
The main problem is that you have to unwrap the mesh yourself (providing non-overlapping UV's for every face) before passing it to Sunflow. Of course Blender offers unwrapping tools that can do this for you, but if you unwrap every mesh individually, you will likely have (a) a LOT of separate lightmap textures (b) maybe some of wasted space in each lightmap texture (c) inconsistent lightmap resolution in your level (some meshes with high lightmap resolution, others with low lightmap resolution). A tool like FSRAD "unwraps" meshes automatically and splits large polygons if necessary to ensure consistent lightmap resolution everywhere (you specify the desired resolution and maximum allowable lightmap size, FSRAD splits polys if needed to use that lightmap size). Also, AFAIK, FSRAD tries to optimize lightmap usage so that faces from different meshes may use the same lightmap, and the lightmaps for the faces are "packed" to squeeze as many faces as possible into each lightmap. This reduces the number of lightmap textures and thus the texture-switching burden on the graphics card.
Sunflow still has a few quirks (bleeding on lightmap edges), but overall it's quite powerful and seems to be gaining momentum, so it might be worth checking it out and adding it to your tool set. Oh, and it's written in Java, so it runs on all Java-supported platforms like Linux, Mac OSX, and other operating systems.