MoneyWorks 6 is compatible with Lion, the new Mac OS (10.7). MoneyWorks 5.3 also appears to work in Lion (but no further updates will be issued if compatibility problems turn up). MoneyWorks 4 (and earlier versions) will not run on Lion since it predates Apple’s switchover to Intel processors and Apple have removed the compatibility layer (Rosetta) from Lion that allowed older software to run on Leopard and Snow Leopard.
Lion also introduces a variety of new technologies such as Versions and iCloud. These were not designed to support complex databases, and hence do not appear to be a good fit for MoneyWorks at this time. This does not mean that you cannot use iCloud as a backup for your MoneyWorks files, it just means that you cannot run your MoneyWorks file directly from iCloud.
Important Note for MoneyWorks 4 Users
You must upgrade your MoneyWorks data file(s) to MoneyWorks 6 before you upgrade to Lion. The process of converting a MoneyWorks 4 datafile to later versions of MoneyWorks relies on Rosetta, which, as noted above, is not available in Lion.