We are a web portal with about twenty or thirty verticals that we want
to bring traffic to our site.  We are in the process of optimizing our
site for search engine submission, but are concerned that if we
include the relevant keywords in our metatags, we'll be penalized for
keyword spamming.  We're looking for suggestions or best practices
from other web portals as to how to optimize our site for search
engines without being penalized as spammers?

Just a note, search engine optimization doesn't have as much as you
would think to do with meta tags, its mainly about links, content and
overall positioning of keywords you want to get ranked for.

Page titles are also of extreme importance, i think you should maybe
rephrase your question to say something like "what would be the best
way to optimize my site for certain keywords and to get a specific
targetted audience" You will get much more for your money that way, as
the answer will actually help you improve

Additionally take a look around
http://www.internet-marketing-research.net/ these guys have some
really easily understandable articles which will give you an endless
amount of insight

Hello

I would suggest you use the following tips
1. Feature the keywords separately and together in
<Title>
<meta content>
<meta description>
<h1> One near the top of the html and one somewhere in the middle of the page
<h3> in the footer of the page

2. Build an introductory paragraph of 30-50 words that appears near
the top of the html file. Feature the keywords and combinations
prominently

3. Use the keywords in the urls to the subpages of the site

4. Pepper the keywords through the pages all the way to the bottom of the html

5. name the graphics files using the keywords

6. Use one or two alt tags in the graphics with the keywords

7. build a sitemap and link to it from footers of all pages in the
site.

8. Include a section for "links". Use the page or pages for exchanging
links with websites in the same business. Put links on this page and
subsequent pages to their home page and ask them to add your home page
link to their links page(s). Too many direct home page
to home page exchanges can trigger Google to demote your listing. Make
sure that you "anchor" the link that you supply to your partners in
the exchange with the keywords that you have chosen to feature.

9. Get listed in "directories" like DMOZ and Yahoo. 

10.Get your contents so that people have a reason to revisit.

Thanks
Shabbir Bhimani