Presentations and posters can be made in Inkscape.
Scientific material often requires equations.
Inkscape doesn’t have an equation editor.
It is possible to compose math in LaTeX, typeset (compile) it to DVI, and convert DVI to SVG using dvisvgm.
Use the command
dvisvgm filename.dvi -n to specify that the characters should be converted to paths.
Update: For those who prefer a GUI interface to working with the command line, you can achieve similar results with http://viereck.ch/latex-to-svg/. (Thanks to Peter for sending in the link.)