First and foremost, your site position in search engines is primarily determined by how many popular sites link to your site.
Second, this in turn depends on a) how much relevant, interesting and frequently updated content you have on your site and b)your outreach work on having other relevant sites link to yours.
Third, it depends on how competitive and generic your target keywords (what keywords do you want people to find you by).
Then you have some basic mechanics like having good page titles (which you can setup in Wild Apricot - see http://help.wildapricot.com/display/DOC/Search+Engine+Tools+-+Page+Title+and+Meta+Tags ); having site built in a way that all links are crawlable (true for WA);
The above answers for ~80-90% of SEO success

Here is one example: do a google search for 'canada internet marketing':

http://www.google.com/search?q=canada+internet+marketing  

One of the top links should be Wild Apricot client www.aimscanada.com - and they got there for these competitive keywords by doing NO proacitve SEO whatsover and using no special tools at all. Just by having many people link to them.

You can be assured that we will keep adding SEO features to WA but with current features high search position can already be achieved. Whatever platform you use, good position requires lots of work and no software has a magic bullet.