Lightroom 2.1 is out to fix a few bugs, improve stability and performance, and provide the last Abode Camera Raw profiles. You should be prompted to download and install the upgrade when you run Lightroom, or you can get it on the Adobe site.
One of the fixes I wasn’t aware of is that if you upgraded from v1.4 to v2.0 your keywords will have all been set to “don’t export”. If this has happened to you and you only have a small number of keywords then it’s probably easiest to just manually edit them and change them to be included on export.
However if, like me, you have a large number of keywords, you can download a script from the Adobe site (link below) to either set all keywords to export, or if you still have your old v1.x catalog on your system (unless you deliberately deleted it you probably will) it can read the setting from that and update your keywords.