Wishful thinking. But unlikely for the following reasons:
1) Google don't tend to wait for a seminar to announce new products/services
2) If they wanted to release Picasa for Mac then they could've done it ages ago. After all, Picasa for Linux has been around since May 2006 - normally considered a less important platform than Mac OS. And it's not as if Google is just ignoring the Mac market - it has a specific focus on Macs, having released the "Picasa Web Albums Exporter" iPhoto plugin and the "Picasa Web Albums Uploader" application for Mac.
3) I reckon that Google and Apple have a pretty close working relationship and intentionally avoid competing with each other. The main photo management software for the Mac is iPhoto, the cornerstone of the iLife suite. It would be very unhelpful if Google competed with them in this market. I believe this is why Google have released Picasa Web Album software for Mac but not the Picasa application itself. For evidence of the close working relationship just look at the fact that the Google CEO (Eric Schmidt) is also a director of Apple - and look how Google and Apple have worked so closely on the iPhone. I could even see a merger of these two organisations at some point in the future (it has been discussed before).
Clearly this isn't decisive evidence but there is more evidence against a release of Picasa for Mac than for it!
