Contrary to a popular belief, it IS in fact possible to show multiple calendars from a Google Calendar account, including the special calendars (i.e. Weather and Week of the Year). And it is really quite simple to do.
I’m going to start off by assuming you know how to add a Google account to Lion. If not, that’s pretty simple too: just click Apple->System Preferences, in the System Preferences Window select Mail, Contacts, and Calendar (under Internet & Wireless), then add away.
Once you have your accounts setup, go ahead and open up iCal. Once in iCal, select the iCal menu, then click Prefences… In the window that comes up, click on Accounts, then select the account that has the calendars you want to show up. You should see a tab that says Delegation, click that and wait a moment for iCal to load the list of your calendars. Just click the ones you want to show up. Repeat for each account your want to view calendars from.
When you’re finished, just close the preferences window, and to toggle calendars, just click the aptly-named Calendars button, then in the Popover that appears, you’ll find the calendars you selected. (called Delegates for some reason)