Most existing applications do not have any semantic technologies built in, and the authors of new applications may be unfamiliar the possibilities such technologies offer. In some cases, however, these technologies can add value to an application without requiring elaborate retrofitting or redesign. This is most likely how semantic technologies will become common within the astronomical developer community, and I will briefly discuss this process. I'll also show how we have made this possible in three cases.
The SKUA project is developing a service which allows applications to share per-user state with other instances of the same application, other cooperating applications, or other users with, crucially, some lightweight semantic enhancement at the level of thesauri. I'll demo this working in the AstroGrid VOExplorer application.
The Explicator project is developing services to support users exploring vocabularies, and (via XML-RPC) applications finding an appropriate vocabulary term from an input string.
The AGAST project is developing an access-control decision service which uses semantic-web-style reasoning to provide flexible policy management to an otherwise naive application.