If the rumors are correct, Mac OS X 10.7 (otherwise known as Lion) will be released very soon.
Currently, Express 3.3.2 and Nisus Writer Pro 2.0 are compatible with Lion, apart from a few issues that we have identified so far. These issues will be fixed in Express and Pro 2 in upcoming releases. These updates should be released within a week. Pro 2 will receive a handful of fixes for issues that appeared after its release (including fixes for the page number display bug and the Bookends issue).
The other big issue that will come up, if the reports are true, is that Rosetta will no longer be included in OS X.
(A quick primer: Rosetta is software that enables PowerPC applications to run on the newer Intel Macs.)
Rosetta was introduced with Mac OS X Tiger (10.4) and was also included with Leopard (10.5). It then became an optional installation with Snow Leopard (10.6). That is apparently where it will end.
How does this relate to Express and Pro? While both of these applications are universal binaries (which can run on both PowerPC and Intel Macs) the file importers were PowerPC until recently. Since that means using Rosetta, this presents a problem.
In the case of Pro, we have already switched the file importer to Intel, so there is no problem for owners of Intel Macs. We still offer a version with a PowerPC importer, but moving forward we will phase out PowerPC support.
Express uses a different file importer that is only PowerPC. With Rosetta (allegedly) being phased out we will switch Express to use the file importer built into OS X, which is compatible with both Intel and PowerPC Macs.
So that is the update. More information will follow once we get close to release.