The ODF 1.0 specification (PDF) does support font embedding, however neither LibreOffice nor OpenOffice have it implemented at this time. There are only two ODF implementations that support font embedding to some regard, which are Calligra and WebODF.
For LibreOffice there is a ticket fdo#42195, but there is also an OpenOffice ticket going way back to 2003 ooo#20370.
Embedded fonts have come up at various ODF Plugfest meetings, but general support is still lacking at this time. Let’s hope this improves soon…
The implementation can embed fonts by either adding it to the packaged (zipped) ODF file in a Fonts/ directory and referencing that file using <svg:font-face-uri>, or by base64-encoding the file (in case of a Flat ODF file).
Update: Font Embedding is implemented and will ship as part of LibreOffice v4.1 (July 2013) using the ODF v1.0 specification.