The announcements web part that is displayed on a team site will limit the amount of body text that is displayed. Here's a simple way to expand the size of the displayed announcements web part on a team site while retaining a similar format.
Start with a Team Site and modify an announcement to contain a large amount of text. This example uses an extreme amount of text!
Next, open the page with SharePoint Designer. Click on the announcements web part and you'll notice a List View Options button is displayed in the upper left corner of the web part. Click on Change Layout.
Select the Layout tab and select the layout that is 3rd or 4th from the bottom of displayed layouts and click OK.
Click Yes to the Site Definition Page Warning dialog. You are now "un-ghosting" the page from the site definition and a custom version of the page is being stored in the database. Save your work in SharePoint Designer.
Reload the page in your browser and look at the results. Notice the additional fields displayed at the bottom of the announcement. Let's get rid of them.
Go back to SharePoint Designer and click on the List View Options button again but this time select Fields. Highlight the fields you want to remove and click the Remove button and then click OK. Save your work in SharePoint Designer and go back and reload your browser to see the results.
The extra fields are now gone.