(I saw a link to this from the Wikipedia entry on esent)
A company called iiobo has released a C++ toolkit for using esent (I'm guessing they developed it for internal use). I haven't looked at the code, but their website says that they have:
"C++ classes that provide a higher level abstraction of Extensible Storage Engine e.g DbCursor, DbTable, DbSchema etc. These well designed abstractions allow you to seamlessly work with transactions and other database considerations inside object-oriented C++ code."
Their code is released under the BSD license.